Users can attach image to posts

* run migration to add image column to post
* install paperclip gem
* modify development.rb in config/enviroment
* modify post controller to permit image
Removing images
* Show image, if only there is one
Fix image size after upload
fix error
fixed error
fix error
fix error
Merge branch 'ik-post-image' of https://github.com/reshleman/craigstr into ik-post-image
Merge branch 'master' of https://github.com/reshleman/craigstr