Version 4.0.0

Breaking changes:

• device.create_qod_session() now requires duration as a mandatory parameter
• device.get_congestion() now returns a list of Congestion objects

Changes:

• device.verify_location() may now return a "PARTIAL" result if the device is
  partially inside the verification area

Fixes:

• Previously due to a miscommunication device.sessions() would return all
  created sessions. These have now been correctly limited to device-specific ones