global: puppet preparations

* Reorganises branches in order to align with Puppet configuration.

* Fixes travis to test against specific Invenio operations branches.

* Changes Python version from 2.6 to 2.7.

* Adds initial documentation stub.

Signed-off-by: Lars Holm Nielsen <lars.holm.nielsen@cern.ch>
tests: default test requirements per branch

* Fixes issue with builds not passing in local github branches due to
  requirements for branch not being found.

Signed-off-by: Lars Holm Nielsen <lars.holm.nielsen@cern.ch>