adjust sponsor logo display

- add 2ndq logo with white background so it shows up on the main footer
- use 2ndq transparent logo on the sponsor page
- put sponsors on individual lines on sponsor page
- faff about with spacing of sponsor images on main footer
Merge branch 'master' of git://github.com/sfrost/pgopen2014
Merge pull request #20 from gorthx/master

more tinkering with the sponsor logos