Puppet Support

Converts puppet Module to mongoengine.

The following are done:

• model definition
• upload importer
• forge importer
• directory importer
• copy importer
• puppet_distributor
• puppet_install_distributor
• puppet_file_distributor
• wholerepo profiler
• migrations
• forge API
• adds a migration to drop specific because they were redundant
• adds 2.8.0 release notes
• adds a release note about the index dropping

https://pulp.plan.io/issues/875 closes #875