Getting rid of teams, code changes

@alexcouper this is not ready, just to show work in progress from some hacking around.

I've reorganised some stories in TP according to our discussion of simplifying ployst and removing teams for now. This includes some code changes in JS and backend.

TODO:
- [ ] redo the ownership checks/mixins to work with the new structure.
- [ ] fix failing tests
- [ ] write tests for the new projects code (JS in particular) which will in part be a port of the former team tests

Follow-up stories once this PR is done will include:
- Move the github-based repo selection (now in providers) to within projects, as discussed
- Reconsider the basic UI structure. I liked the approach of making good use of horizontal space by putting menus to the sides, but it calls for too much coding effort for custom UI components, so I'll bite the bullet and go for a canned framework. I want to try this: https://material.angularjs.org rather than just default to bootstrap3.
Oh and we should also reconsider this, by letting you use GH handle or select users from your organisations.