Prune failed delayed jobs periodically

[#73904862]

Signed-off-by: Matthew Sykes <matthew.sykes@gmail.com>
Upgrade Sequel

- Serialized attributes have symbols for keys until they are reloaded from the db
- Page 0 no longer exists in paginated responses, it is always page 1 now.
- Fixed bug in preloaded_object_serializer where it would load to_one associations before checking them

[#73151346]

Signed-off-by: Zach Robinson <zrobinson@pivotallabs.com>
Remove savepoint: true from code and specs now that auto_savepoint works

[#73151346]

Signed-off-by: Eric Malm <emalm@pivotallabs.com>
Remove service_instances integration tests.

- the v2 service instance tests were already covered in broker api compatibility tests
- simplify user provided service instance tests
- remove fake service broker since it is no longer needed

[#74230146]
remove unnecessary test
Consolidate all Rspec.configure blocks into spec_helper

[#72476438]
Fix flaky spec

- Timecop.travel unfreezes time
Fix flaky specs

all.last returns an array first, and then the last element out of it.
Postgres does not guarantee order, so the results of "all" can be unexpected.
Pull RspecApiConfiguration out of before :all

Remove VCAP::CloudController::SecurityContext.clear from before :all, doesn't seem needed

[#72476566]