Use regular AR query instead of raw SQL.

git-svn-id: http://svn.redmine.org/redmine/trunk@13496 e93f8b46-1217-0410-a6f0-8f06a7374b81
Code cleanup: use #project_condition.

git-svn-id: http://svn.redmine.org/redmine/trunk@13497 e93f8b46-1217-0410-a6f0-8f06a7374b81