Require the version of pypuppetdb we use.
Require the version of pypuppetdb we use.

In production, we use a debian packaged version of pypuppetdb, which
is built from the NeCTAR-RC fork. Specify that fork here to avoid confusion.
This might also help with anywhere we are using virtual environments and
installing with pip.

Change-Id: Ibd4b391b882e84ac05b6e9fca7f974ba972ef741

NeCTAR-RC/external_naginator