Python: initial port of UAVTalk parser

Consolidate the parsing code into a class and port the existing
code from the flight side
Python: log parsing using the UAVTalk class

This method validates the checksums and uses a core class
to handle all of the UAVTalk parsing on the data streams.
No handling of communications is done yet.
Python: add ability to send an object update

The UAVTalk class can now format a UAVTalk message update for an
object and send it with

parser = UAVTalk(uavo_defs)
packet = parser.sendSingleObject(obj)

The packet generated can then be sent out whatever physical link
layer you would like.
Python: documentation for uavtalk.py