Populating columns dialog with available/selected columns.
Have a dummy sortable select2 for columns modal. Not wired up yet.
Wired up columns controller to an extent.

Still some ui issues - select needs to be deactivated whilst loading. Now waiting for refactor so that wp table watches the query columns and not the columns scope variable.
Wired up columns select to query columns.
Fixed broken tests related to query service.
Fixed bug relating to groupBy.
Introduced caching of available columns in query service.

Solves problem of select2 not having available values when loading the columns modal.
Added a test for queries helper and cleaned up a bit.
Merge branch 'feature/ng-toolbar-column-select' into feature/column-context-menu

Conflicts:
	app/assets/javascripts/angular/controllers/work-packages-controller.js
	app/assets/javascripts/angular/services/query-service.js
Fix typo
Consolidate QueriesHelper and WorkPackagesTableHelper
Refactor column dialog