Use simplecov for code coverage, rcov does not support ruby>=1.9.

git-svn-id: http://svn.redmine.org/redmine/trunk@13691 e93f8b46-1217-0410-a6f0-8f06a7374b81
Use scope.

git-svn-id: http://svn.redmine.org/redmine/trunk@13692 e93f8b46-1217-0410-a6f0-8f06a7374b81
Removed broken and unused method added in r5313.

git-svn-id: http://svn.redmine.org/redmine/trunk@13693 e93f8b46-1217-0410-a6f0-8f06a7374b81
Get version ids with a single query (was n+1).

git-svn-id: http://svn.redmine.org/redmine/trunk@13694 e93f8b46-1217-0410-a6f0-8f06a7374b81