Add index template for Slate format

Rather than hard coding the front matter and api explanation rendering,
use a mustache template for the index.

Author: Leonard Chin

lib/rspec_api_documentation/views/slate_index.rb

@@ -1,6 +1,10 @@
 module RspecApiDocumentation
   module Views
     class SlateIndex < MarkdownIndex
+      def initialize(index, configuration)
+        super
+        self.template_name = "rspec_api_documentation/slate_index"
+      end
     end
   end
 end

lib/rspec_api_documentation/writers/slate_writer.rb

@@ -21,14 +21,7 @@ def markup_example_class
       def write
         File.open(configuration.docs_dir.join("#{FILENAME}.#{extension}"), 'w+') do |file|
 
-          file.write %Q{---\n}
-          file.write %Q{title: "#{configuration.api_name}"\n}
-          file.write %Q{language_tabs:\n}
-          file.write %Q{  - json: JSON\n}
-          file.write %Q{  - shell: cURL\n}
-          file.write %Q{---\n\n}
-
-          file.write configuration.api_explanation if configuration.api_explanation
+          file.write markup_index_class.new(index, configuration).render
 
           IndexHelper.sections(index.examples, @configuration).each do |section|
 

spec/writers/slate_writer_spec.rb

@@ -22,7 +22,7 @@
       FakeFS do
         template_dir = File.join(configuration.template_path, "rspec_api_documentation")
         FileUtils.mkdir_p(template_dir)
-        File.open(File.join(template_dir, "markdown_index.mustache"), "w+") { |f| f << "{{ mustache }}" }
+        File.open(File.join(template_dir, "slate_index.mustache"), "w+") { |f| f << "{{ mustache }}" }
         FileUtils.mkdir_p(configuration.docs_dir)
 
         writer.write

templates/rspec_api_documentation/slate_index.mustache

@@ -0,0 +1,8 @@
+---
+title: {{ api_name }}
+language_tabs:
+  - json: JSON
+  - shell: cURL
+---
+
+{{{ api_explanation }}}