Fix sponsor logos

- make nilenso background medium
- add github back to associate sponsors
- move logos around to balance background colours
Remove links to doattend

- as ticket sales have closed
Update talks.html
Merge pull request #71 from SatishTalim/master

Added some details of speakers
Updated talks for Aaron and Andy
Added Schedule
Merge pull request #72 from gautamrege/master

Added Aaron and Andy profiles; enabled the schedule
Fix schedule and doattend links

- uncomment schedule everywhere
- comment doattend everywhere
[sd] merged.