Added a fallback for mini_magic + ImageMagic for platforms where it is more than difficult to compile the ImageResizer

Gemfile

@@ -31,3 +31,7 @@ gem "whenever", :require => false
 group :development do
   gem 'pry'
 end
+
+group :osx do
+  gem 'mini_magick'
+end

Gemfile.lock

@@ -76,6 +76,8 @@ GEM
     method_source (0.6.0)
       ruby_parser (>= 2.0.5)
     mime-types (1.16)
+    mini_magick (3.3)
+      subexec (~> 0.1.0)
     mocha (0.9.12)
     multi_json (1.0.3)
     net-http-digest_auth (1.1.1)
@@ -130,6 +132,7 @@ GEM
       hike (~> 1.2)
       rack (~> 1.0)
       tilt (~> 1.1, != 1.3.0)
+    subexec (0.1.0)
     super_exception_notifier (3.0.13)
       actionmailer
       rake
@@ -165,6 +168,7 @@ DEPENDENCIES
   mechanize
   memcache-client
   meta_search!
+  mini_magick
   mocha
   nokogiri
   pg

lib/danbooru_image_resizer/danbooru_image_resizer.rb

@@ -1,4 +1,8 @@
-require 'danbooru_image_resizer/danbooru_image_resizer.so'
+begin
+  require 'danbooru_image_resizer/danbooru_image_resizer.so'
+rescue LoadError
+  require 'danbooru_image_resizer/danbooru_image_resizer_fallback'
+end
 
 module Danbooru
   def resize(file_ext, read_path, write_path, output_size, output_quality)

lib/danbooru_image_resizer/danbooru_image_resizer_fallback.rb

@@ -0,0 +1,11 @@
+module Danbooru
+  def resize_image(extension, original_path, destination_path, width, height, quality)
+    require 'mini_magick'
+    image = MiniMagick::Image.open(original_path)
+    image.resize "#{width}x#{height}"
+    image.format extension
+    image.write destination_path
+  end
+
+  module_function :resize_image
+end