update grape to 0.3.1 for ruby 2.0 support.

closes #2300

add grape-entity, that is split from grape 0.3.0.
remove usage of deprecated error_format, that is removed in grape 0.2.3.

Merge branch 'state-machine-stage-2' of https://github.com/Undev/gitlabhq into Undev-state-machine-stage-2

Conflicts:
	app/models/merge_request.rb

Show only ≤16 lines of codes in a discussion in a MR (issue #2860).

Since search_autocomplete_source rendered with raw all human input should be sanitized to prevent XSS

System hooks code & logic refactoring

Remove function 'check_issue_1059_shell_profile_error' from check.rake as it is not needed anymore

Fix WebHook and special symbols in credentials

Add title for "Remove from team" button

Add transition on search box

It's kind of cool trend to use animated-expanding search box nowadays.
E.g. see Github.