Engine: Updating katello reset DBS to only reset Pulp and Candlepin.

This will not reset the Katello/Foreman DB like it did previously. That should
be done through the normal Foreman setup. This could be moved out to a rake
task in the future, but for now this is a utility method when needing to
reset your development environment.
Merge pull request #3242 from ehelms/engine-reset-dbs

Engine: Updating katello reset DBS to only reset Pulp and Candlepin.