[Twisted-Python] Releasing 12.1

[Itamar Turner-Trauring]

Once 12.1 is out, we'll be able to drop Python 2.5 support in trunk. 
This will make life easier for one of our Google Summer of Code students 
who will be working on the start of Python 3 support, so it'd be good to 
get it done soon. In order to release 12.1, we need:

1. To finish code reviews of remaining 12.1 tickets and merge: 
http://twistedmatrix.com/trac/query?status=assigned&status=new&status=reopened&group=status&milestone=Twisted-12.1

These include two gtk3 tickets: gtk3 is new in 12.1, and I'd like to 
ship it bug free and feature complete. There's also a couple of tickets 
which will make epoll the default reactor on Linux. While not strictly 
necessary, they should be easy enough to get merged and it's a great 
feature to have in; if they become a bottleneck we can drop this and 
wait until the next release.

2. A volunteer to do the release. Any takers?

-Itamar