Renamed add_bulk_readings to add_list.

-Need to add old implementation of add_bulk_readings back for
 backwards compatability.
Add old implementation of add_bulk_reading back in.
Add backwards compat to add_reading.
Resurect add_reading version, add add_reading_bulk version.
Fix import error.
Adjust test file for bulk testing.Add error handling for new exception SensorReadingCollision.
Add error handling for new exception SensorReadingCollision