Restructure Drydock so that blueprints are instances in the DB

Summary:
(this diff used to be about applying policies to blueprints)

This restructures Drydock so that blueprints are instances in the DB, with an associated implementation class. Thus resources now have a blueprintPHID instead of blueprintClass and DrydockBlueprint becomes a DAO. The old DrydockBlueprint is renamed to DrydockBlueprintImplementation, and the DrydockBlueprint DAO has a blueprintClass column on it.

This now just implements CAN_VIEW and CAN_EDIT policies for blueprints, although they are probably not enforced in all of the places they could be.

Test Plan: Used the create-resource and lease commands. Closed resources and leases in the UI. Clicked around the new and old lists to make sure everything is still working.

Reviewers: epriestley, Blessed Reviewers

Reviewed By: epriestley

CC: Korvin, epriestley, aran

Maniphest Tasks: T4111, T2015

Differential Revision: https://secure.phabricator.com/D7638