This PR allows user to import puppet classes from a specific environment manually, from both GUI and Rake.

Developers can click a button to sync the classes they recently created/updated/removed in a specific environment to Foreman, without waiting for the lengthy full class/environment sync to be finished by "ruby193-rake puppet:import:puppet_classes[batch]"

https://github.com/theforeman/foreman/pull/1204
https://github.com/theforeman/foreman/pull/1215