Extract logic from drain hook to bring it under test

It is not yet under test, but we plan to do this shortly

Signed-off-by: Kai Zhang <kaizhang@cn.ibm.com>
Add unit tests for Drain class in lib/cloud_controller

[#63767870]

Signed-off-by: Eric Malm <emalm@pivotallabs.com>
Move services business logic from app/models to lib and change namespace

-now lives under VCAP::Services
[#66460516]
Rearrange logging to make extracting deletion logic easier

[#68820074]

Signed-off-by: Matthew Sykes <matthew.sykes@gmail.com>
Introduce Repository for AppUsageEvents

So code to create these live close to each other and we can see discrepencies more easily

[#68820074]

Signed-off-by: Matthew Sykes <matthew.sykes@gmail.com>
Respect UAA scopes during access control