Add voting to release process

[Tom Zeller]

As part of the release process for IdP 3.1.0, I suggest we collect
votes via email ala the Apache Voting Process[1].

My motivation for this is to make sure our efforts are coordinated,
especially since we have less frequent dev calls now.

I guess it would be nice if the release notes for the release were
figured out for the release vote, so folks can have a better idea of
what they are voting for.

Thoughts ?

Thanks.

[1] http://www.apache.org/foundation/voting.html