Create "Get involved" page

[caseycesari]

This page could be a mash up of discussion threads, hightlighted tweets, the form to signup for the public insight network and some links to apps that ask for participation (like schoolhousewatch). see http://www.propublica.org/getinvolved

[caseycesari]

We could list our events here too.

Perhaps we can call it something other than get involved, too.