Replace mimemagic with marcel gem

lib/paperclip.rb

@@ -64,9 +64,8 @@
   require "mime/types"
 end
 
-require 'mimemagic'
-require 'mimemagic/overlay'
 require 'logger'
+require 'marcel'
 require 'terrapin'
 
 require 'paperclip/railtie' if defined?(Rails::Railtie)

lib/paperclip/content_type_detector.rb

@@ -68,7 +68,7 @@ def type_from_file_contents
 
     def type_from_mime_magic
       @type_from_mime_magic ||= File.open(@filepath) do |file|
-        MimeMagic.by_magic(file).try(:type)
+        Marcel::Magic.by_magic(file).try(:type)
       end
     end
 

paperclip.gemspec

@@ -28,7 +28,7 @@ Gem::Specification.new do |s|
   s.add_dependency('activesupport', '>= 4.2.0')
   s.add_dependency('terrapin', '~> 0.6.0')
   s.add_dependency('mime-types')
-  s.add_dependency('mimemagic', '~> 0.3.0')
+  s.add_dependency('marcel', '~> 1.0.0')
 
   s.add_development_dependency('activerecord', '>= 4.2.0')
   s.add_development_dependency('shoulda')