Image url

Created a field in the database, associated forms and views, spec tests, and validator in lib/validators that allow a user to include an image with their project description by linking to a file hosted on a whitelisted website.

https://www.pivotaltracker.com/story/show/80235250
ok, it doesn't show in my sublime, but I deleted back to the end of the preceding line and hit return, so it should be gone now