Revert "Flapjack support for puppet"

Reverts sensu/sensu-puppet#284

I'm going to revert this for a few reasons:

This by default will install the flapjack extension for all users
The flapjack plugin is pulled directly from GH meaning installs are not idempotent (that file changes over time)
- which leads to we need a generic method for installing extensions as well as configuring them