Release Flocker-0.3.2

Here's how to test:
 * http://doc-dev.clusterhq.com/gettinginvolved/infrastructure/release-process.html#reviewing-preparing-for-a-release

But actually it's simpler to download the vagrant tutorial box file from buildbot
 * http://build.clusterhq.com/boxes-flocker?branch=release/flocker-0.3.2

And perhaps it's not necessary to do acceptance tests since there have been no further changes in master since 0.3.1 was tested yesterday.

Fixes https://clusterhq.atlassian.net/browse/FLOC-1014