WIP Made a basic sort dialog which is wired up to queries service set sortation.

Once the refactor is done and the wp table is wired directly to the query then hopefully this should update the sortation.
WIP wiring up initial filter values.
Wired up sorting modal to current query sortation.

Not yet updating table when sortation is changed.
Temp solution - moved sortation watcher to wp controller.

Also copied over available columns caching from columns branch.
Always have 3 sort elements in sort selection modal.
Moved modals back into dropdown directive...:>
Reverted Gemfile.lock to that from dev-angular. Must have accidentally committed it.
Merge branch 'dev-angular' into feature/ng-toolbar-sort-by
Column headers now displaying first sort element up/down arrow.
Merge branch 'feature/ng-toolbar-sort-by' of github.com:opf/openproject into feature/ng-toolbar-sort-by
Merge branch 'dev-angular' into feature/ng-toolbar-sort-by

Conflicts:
	app/views/work_packages/index.html.erb
Merge pull request #1306 from opf/feature/ng-toolbar-sort-by

Feature/ng toolbar sort by