generates migration for project_bookmarks
creates bookmark relationships between Projects & Usersj
adds bookmark/unbookmark links to project page

Adds basic bookmark/unbookmark functionality to a project page.
Layered on top of this will be jquery functionality so that a page reload
isn't required.
ajaxify project bookmarking
adds bookmarks to user dashboard
adds bookmark count to project page
adds list of bookmarks to user profile page
Merge pull request #19 from feastongood/project_bookmarks

Project bookmarks