Backend Filtering

This pull request adds publish filtering to the core. 

@andrewminton, @brendo, @designermonkey, there are still a few general issues:

- [ ] we need to think about the right variable names, see https://github.com/symphonycms/symphony-2/blob/2da1a906a6e5df689ee5d0b6115719adf8798352/symphony/content/content.publish.php#L22-L24
- [ ] incompatibilies should be set on a field level in my eyes, see https://github.com/symphonycms/symphony-2/blob/2da1a906a6e5df689ee5d0b6115719adf8798352/symphony/content/content.publish.php#L21
- [ ] filtering options should be added to the Symphony options along with the other environmental information, see https://github.com/symphonycms/symphony-2/blob/integration/symphony/lib/toolkit/class.administrationpage.php#L351-L378, which leads to the questions if all functions are in the right file at the moment
- [ ] styles should not use an id selector
- [ ] script initialisation should be added to `backend.views.js`