ds 6.x-1.4

- #922114 by Shawn DeArmond: Exporting ds features properly requires strongarm.
- #931510 by joelstein: fix occasional features errors when reverting.
- #848478 by swentel: add relationship to views.
- #855888 by swentel: add support for foreign tables and modules in views fields.
- #887530 by swentel: heigher delta for weights.
- #886684 by swentel: check if module exists in ds fields plugin.
- #872708 by swentel: extra info on the start screen.
- #933876 by swentel: Fix tokens fieldset for rubik.
- Added an new tool tab to export a stylesheet skeleton.
- Add option in display plugin to change build modes per row via the UI.
- Add option in display plugin to group on a sort field per row via the UI.
- Fix notices in views fields.