upgrade rmagick to 2.14

And replace deprecated requiring "RMagick" to "rmagick".

git-svn-id: http://svn.redmine.org/redmine/trunk@14170 e93f8b46-1217-0410-a6f0-8f06a7374b81

Gemfile

@@ -32,7 +32,7 @@ end
 platforms :mri, :mingw, :x64_mingw do
   # Optional gem for exporting the gantt to a PNG file, not supported with jruby
   group :rmagick do
-    gem "rmagick", "~> 2.13.4"
+    gem "rmagick", ">= 2.14.0"
   end
 
   # Optional Markdown support, not for JRuby

lib/redmine.rb

@@ -18,7 +18,7 @@
 require 'redmine/core_ext'
 
 begin
-  require 'RMagick' unless Object.const_defined?(:Magick)
+  require 'rmagick' unless Object.const_defined?(:Magick)
 rescue LoadError
   # RMagick is not available
 end