Change Propose a badge to nominate someone

* Creates migration to change badge proposal to nominate someone
* Changes db schema
* Rename badge proposals controller to nominee user controller
* Rename badge proposal model to nominee user model
Change Propose a badge to nominate someone

* Fix problems with user model
* Fix params and methods of nominee users controller
* Remane folder badge proposals to nominee users
* Fix link in user show view
* Finx badge proposal resource to nominee user in routes file
Change Propose a badge to nominate someone

* Rename badge proposal specs to nominee users specs
* Fix all related specs
Merge pull request #29 from crowdint/feature/change-propose-badge-to-nominate-someone

Feature/change propose badge to nominate someone