Added head method type (ruby-grape#408)

Fix: HEAD method support.

Author: kzaitsev

CHANGELOG.md

@@ -6,6 +6,7 @@
 
 #### Fixes
 
+* [#408](https://github.com/ruby-grape/grape-swagger/pull/408): fix fails when point with head method present - [@Bugagazavr](https://github.com/Bugagazavr)
 * [#405](https://github.com/ruby-grape/grape-swagger/pull/405): corrects documentation of versions [issue #403](https://github.com/ruby-grape/grape-swagger/issues/403) - [@LeFnord](https://github.com/LeFnord).
 * [#399](https://github.com/ruby-grape/grape-swagger/pull/399): makes param description optional, solves [issue #395](https://github.com/ruby-grape/grape-swagger/issues/395) - [@LeFnord](https://github.com/LeFnord).
 

lib/grape-swagger/doc_methods/status_codes.rb

@@ -8,7 +8,8 @@ def get
             post: { code: 201, message: 'created {item}' },
             put: { code: 200, message: 'updated {item}' },
             patch: { code: 200, message: 'patched {item}' },
-            delete: { code: 200, message: 'deleted {item}' }
+            delete: { code: 200, message: 'deleted {item}' },
+            head: { code: 200, message: 'head {item}' }
           }
         end
       end

spec/swagger_v2/simple_mounted_api_spec.rb

@@ -23,6 +23,10 @@ class SimpleMountedApi < Grape::API
         { bla: 'something' }
       end
 
+      head '/simple-head-test' do
+        status 200
+      end
+
       desc 'this gets something else',
         headers: {
           'XAuthToken' => { description: 'A required header.', required: true },
@@ -78,7 +82,7 @@ def app
         "swagger"=>"2.0",
         "produces"=>["application/xml", "application/json", "application/octet-stream", "text/plain"],
         "host"=>"example.org",
-        "tags" => [{"name"=>"simple", "description"=>"Operations about simples"}, {"name"=>"simple-test", "description"=>"Operations about simple-tests"}, {"name"=>"simple_with_headers", "description"=>"Operations about simple_with_headers"}, {"name"=>"items", "description"=>"Operations about items"}, {"name"=>"custom", "description"=>"Operations about customs"}],
+        "tags" => [{"name"=>"simple", "description"=>"Operations about simples"}, {"name"=>"simple-test", "description"=>"Operations about simple-tests"}, {"name"=>"simple-head-test", "description"=>"Operations about simple-head-tests"}, {"name"=>"simple_with_headers", "description"=>"Operations about simple_with_headers"}, {"name"=>"items", "description"=>"Operations about items"}, {"name"=>"custom", "description"=>"Operations about customs"}],
         "paths"=>{
           "/simple"=>{
             "get"=>{
@@ -94,6 +98,12 @@ def app
               "tags"=>["simple-test"],
               "operationId"=>"getSimpleTest",
               "responses"=>{"200"=>{"description"=>"This gets something for URL using - separator."}}}},
+          "/simple-head-test"=>{
+            "head"=>{
+              "produces"=>["application/json"],
+              "responses"=>{"200"=>{"description"=>"head SimpleHeadTest"}},
+              "tags"=>["simple-head-test"],
+              "operationId"=>"headSimpleHeadTest"}},
           "/simple_with_headers"=>{
             "get"=>{
               "description"=>"this gets something else",
@@ -142,7 +152,7 @@ def app
         "swagger"=>"2.0",
         "produces"=>["application/xml", "application/json", "application/octet-stream", "text/plain"],
         "host"=>"example.org",
-        "tags" => [{"name"=>"simple", "description"=>"Operations about simples"}, {"name"=>"simple-test", "description"=>"Operations about simple-tests"}, {"name"=>"simple_with_headers", "description"=>"Operations about simple_with_headers"}, {"name"=>"items", "description"=>"Operations about items"}, {"name"=>"custom", "description"=>"Operations about customs"}],
+        "tags" => [{"name"=>"simple", "description"=>"Operations about simples"}, {"name"=>"simple-test", "description"=>"Operations about simple-tests"}, {"name"=>"simple-head-test", "description"=>"Operations about simple-head-tests"}, {"name"=>"simple_with_headers", "description"=>"Operations about simple_with_headers"}, {"name"=>"items", "description"=>"Operations about items"}, {"name"=>"custom", "description"=>"Operations about customs"}],
         "paths"=>{
           "/simple"=>{
             "get"=>{
@@ -168,7 +178,7 @@ def app
           "swagger"=>"2.0",
           "produces"=>["application/xml", "application/json", "application/octet-stream", "text/plain"],
           "host"=>"example.org",
-          "tags" => [{"name"=>"simple", "description"=>"Operations about simples"}, {"name"=>"simple-test", "description"=>"Operations about simple-tests"}, {"name"=>"simple_with_headers", "description"=>"Operations about simple_with_headers"}, {"name"=>"items", "description"=>"Operations about items"}, {"name"=>"custom", "description"=>"Operations about customs"}],
+          "tags" => [{"name"=>"simple", "description"=>"Operations about simples"}, {"name"=>"simple-test", "description"=>"Operations about simple-tests"}, {"name"=>"simple-head-test", "description"=>"Operations about simple-head-tests"}, {"name"=>"simple_with_headers", "description"=>"Operations about simple_with_headers"}, {"name"=>"items", "description"=>"Operations about items"}, {"name"=>"custom", "description"=>"Operations about customs"}],
           "paths"=>{
             "/simple-test"=>{
               "get"=>{