Prepare release for PuppetDB 2.2

This prepares the indexes and source code retrieval for version 2.2. It bumps
2.1 to use a new 2.1.x branch as well. Since we haven't released yet, we still
need to leave the docs as 'pending release' for now.

Signed-off-by: Ken Barber <ken@bob.sh>
Merge pull request #373 from kbarber/maint/master/pdb-prepare-for-release-220

Prepare release for PuppetDB 2.2