v1.2.0

Added:
- This changelog and a patch level in versioning.
- Handling of unsolicited messages from modem as needed with the
  newer pycom firmware.

Changed:
- Update pycom firmware dependency to version v1.20.2.r4. This version
  is tested with modem firmware version 41019 and 41065 (NB-IoT).

Fixed:
- Rework of modem communication module.

Known issues:
- When the mobile network signal is weak the modem gets quite busy with
  handling connection losses and reconnects. This reduces the
  reliability of the communication between modem and the microprocessor.
  Characteristic of this situation are SIM commands failing with APDU
  exceptions such as '6D00' (unsupported command) and similar because of
  transmission errors. A solution to this problem is to position the
  device in a place with better network coverage.

Change LED colors: bright = error, dimmed = OK

send UUID in msgpack as bytearray, not string type

sending data in json format to ubirch json data endpoint

updated ubirch protocol version, fixed wrong unsigned message size in…

… message_verify method

add correct boot.json info

initial commit