Fixed depth maintenance mock task

* The depth ai controller now correctly responds to the
  mock sensor data produced by datafeed/raw/depth/mock.py.

* Refactored the sanitation module so that individual sensors won't
  block each other.

* Fixed general annoyances with the settings file.

* Added a .debug method to grapevine.Communicator objects.

* Re-inserted movement/physical. This module is just forwarding
  messages, but it is where the translation to raw digital values
  should take place.

* Renamed the data pipeline modules. Instead of using "sensor/*",
  we now use "datafeed/raw/*", "datafeed/sanitized/*", and
  "datafeed/filtered/*". If a programmer wishes to insert a mock
  datafeed module, it is possible to create a module in the correct
  location. However, these datafeed communication channels typically
  don't have modules associated with them.

* Cleaned up some more old/dead code.