Move projects out of user profiles and into team profiles

* for each user profile:
	* store the profile slug
	* set the slug to 'user' + profile id (or something)
	* create a new "team" profile with the original slug
	* add the user to the team
	* reassign all the user's projects to new "team" profile
* remove signals keeping username/profile slug in sync
* update tests
* create team based on user affiliation in the signup process
	* test: signup view --> user has one team based on affiliation title
* hide projects section on user profile
* show username (instead of slug) for user profile
* don't allow editing slug on form in user profile
* user profile accessible (only) from openplans.org/profile
* slug-based profile view only searches team profiles
* update the dashboard link in the user menu