Merge pull request pyca#454 from hynek/master

Prepare 16.0.0

Merge pull request pyca#228 from hynek/release-0.15.1

Prepare 0.15.1

Merge pull request pyca#220 from hynek/release-15

Release 0.15

Bump version to 0.14 final

Bump to 0.14a4

Bump to alpha 3

Bump to alpha 2

Hmm maybe start off with a non-final version.