Triggering hooks for certain events

This adds hooks for node-unbound-from-policy, node-bound-to-policy,
node-deleted, node-booted, node-facts-changed, and
node-install-finished

Fixes https://tickets.puppetlabs.com/browse/RAZOR-369
Add `razor hooks` query

The user needs to see which hooks have been instantiated in the application.
This new command will return that list and display the configuration for
each.

Fixes https://tickets.puppetlabs.com/browse/RAZOR-368