Remove commented code
Don't persist broker/catalog changes when update fails

[Finishes #62008174]
Ensure client id is claimed before making UAA client

Also added ServiceDashboardClient.remove_claim_on_client instead of
directly accessing DB.

[Finishes #67885296]
Return correct error responses for invalid bind requests. [#65123304]

- invalid app_guid returns AppNotFound with 404
- invalid service_instance_guid returns ServiceInstanceNotFound with 404

previously they returned 500 errors.
Deleting a service broker deletes UAA clients

[Finishes #62008198]
Rename max_droplet_size to max_package_size

In preparation for surfacing the max app bits package size as a
configurable attribute in cf-release, rename
ccng.packages.max_droplet_size to ccng.packages.max_package_size to more
accurately reflect its purpose.

Also, since ccng.droplet.max_droplet_size is not used in the code,
remove its declaration from config.