Announcement about search for a new maintainer

Seems like we should put this front and center since @j3 @steveklabnik and @haines aren't involved in this project any longer. 

https://twitter.com/andrewihaines/status/546654086138183680
https://twitter.com/steveklabnik/status/544632486379401216
https://twitter.com/j3/status/472586274621382656