Add images to user and projects

Allow users to upload a photo of themselves and a project photo.
This commit includes: configure carrierwave, fog and aws, add
image columns to user and project tables, add image upload field to the user
and project forms, display image thumbnails in index pages, and display
 larger images on show pages. Rationalize some of the related CSS.
This is an entertaining aspect of the "long lines" rule. Since this is actually a single line of text in the html, either I can have a line that's too long, or I can have a trailing space at the end of the first line (in order to have a space between words), or have a leading space at the beginning of the second line. The last option is the only one that doesn't result in comments from hound. :-)