Merge pull request #310 from niedhui/i18n

add i18n support for validation error message
Removed body_params, data sent via a POST or PUT with a supported content-type is merged into params.
Added support for custom parsers via parser. Setting format will automatically remove other content-types and parsers.
Clarified custom formatters, parsed input and non-parsed input availability.
Preparing for 0.2.5 release.
Bump version to 0.2.6.
Fix: support content-type with character set when parsing POST and PUT input.
Fix: CVE-2013-0175, multi_xml parse vulnerability, require multi_xml 0.5.2.
No need to quote multi-xml.
Preparing for a release.
Bump version to 0.2.7.
Add note about stable release.
Correct typo in an api_spec.rb context description

s/muti_xml/multi_xml/
Merge pull request #313 from reedloden/master

Correct typo in an api_spec.rb context description
Fix #309: Added XML support for entities. An XML API will return an error instead of returning a string representation of a response. Failing formatters will get reported with a 500.
Extracted Grape::Entity into the grape-entity gem. Required to start the work needed for #294
Updated documentation, removed grape-entity from required gems.
Linked grape-entity from CHANGELOG.
Attempting spec fix for REE.
Removed empty line.