Generated Collaboration model. Includes user_id, project_id, and string "status", which will originally be generated as pending, and be updated by the creator of the project to accepted or rejected/deleted.
Defined a method user_relation in the projects helper that sets a variable @user_relation to either "owner", "collaborator", nil upon viewing a project page.
Also defined a method for users "user.collabs", that returns an array of all the projects a user is collaborating in. This is in contrast to "user.project", which returns an array of all the projects that the user created.
Fixed some minor bugs, added a button on the project show page that allows a creator to delete the project and someone who is unaffiliated to request to collaborate.
Merge branch 'collab_invites'

Conflicts:
	db/schema.rb