Update model methods
Perfomance updating Project activity sort
Fix tests
Merge branch 'feature/refactoring_scopes_pr' of https://github.com/Undev/gitlabhq into Undev-feature/refactoring_scopes_pr

Conflicts:
	db/schema.rb
Improve perfomance by using project.last_activity_at in project_last_activity helper
Improve migration AddLastActivityColumnIntoProject to use real last activity date if present
Merge branch 'Undev-feature/refactoring_scopes_pr'