Remove extra dependency

`awesome_print` gem is not used in the code and should not be a runtime
dependency.

Initially, it was added as a development dependency in
e406abf. It was used to output debug
information in specs.

But later, it was changed to be a runtime dependency in
05a0085 for no particular reason.

Author: lest

grape-swagger.gemspec

@@ -12,7 +12,6 @@ Gem::Specification.new do |s|
   s.license     = 'MIT'
 
   s.add_runtime_dependency 'grape', '>= 0.12.0'
-  s.add_runtime_dependency 'awesome_print'
 
   s.add_development_dependency 'rake'
   s.add_development_dependency 'shoulda'

lib/grape-swagger.rb

@@ -12,8 +12,6 @@
 require 'grape-swagger/markdown/kramdown_adapter'
 require 'grape-swagger/markdown/redcarpet_adapter'
 
-require 'awesome_print'
-
 module GrapeSwagger
   class << self
     def model_parsers