Adding .img-responsive-horizontal for image display
ImagePost added to Images model

Removes many-to-many relation between posts and their associated images.
getImage URL regex redone

Wasn't supporting all cases initially, but now I'm pretty confident
it's doing what I want it to do.  Also supports junk after the ? mark
to force browsers to send a new GET request.
Adding visibility and shortening Delete button

Manage Posts needs to convey more information, so visibility was added
and the Delete button is shortened to a simple "Delete".
Posts now support images (Closed #59)

Users can upload multiple images, and have them show up in their posts.
Other users that have permission to view a post also have permission to view
the associated images any time they are logged in.  Public posts with images
allow anyone to see an image if they have the URL.

I wanted to say that #61 is done, but I'll need to implement unit tests before that's true.