Add most of the ovscon slides.
Add revalidator talk slides
Update front page ovscon links

Remove agenda (ovscon page has it)
Merge pull request #13 from joestringer/master

Add ovscon content (revalidator talk, link to slides from front page)
ovscon2014: Add slides from John Fastabend (thanks John!).
ovscon2014: Add OVSDB--"use it to configure a switch or track your stamp collection" slides.
ovscon2014: Add Madhu Challa's performance analysis slides.