Fixing the development setup to reduce the dependencies on other apps

The main change is that the mock orgs API only contains HMRC
and using the in memory rummager client from whitehall.

* Uses mock APIs for rummager and organisations APIs
* Drops contacts_search_client as we do not search rummager for search
* Change the server to be thin in dev (to align with other apps)
* Remove rack-mini-profiler probably best to use newrelic when needed