Move company logo from a background image to an img src [PD-526]

Moves company logos to img src rather than being CSS background images. After discussion on Jira with @haliscooper, we determined that this is a good enough improvement over what we had previously. Some users saw every image as broken. There will be more people seeing broken images now, but there should hopefully be a lesser total number of broken images. Fixing what broken images remain is left for a later point in time.

All tests pass.

![2014-10-07-091614_726x502_scrot](https://cloud.githubusercontent.com/assets/3379265/4542670/55aa8f90-4e24-11e4-82a9-17fb56816c1f.png)