Merge pull request #1244 from opf/fix/ruby_2.1.1_hash_select_and_reject

Add patch to fix Rails' hash types with Ruby 2.1.1
strictly regression of Hash#reject in Ruby 2.1.1
add Ruby 2.0 to .travis.yml

Rails 3 on Ruby 2.1.1 is broken.
http://www.redmine.org/issues/16194