Changed TransmissionData to _TransmissionData

Updated the TransmissionData module to fit the updated UML for
Connections.

All tests still pass.
Fixed wrong class name change

TransmissionDataSerializer changed to _TransmissionDataSerializer to
match UML.

I accidentally changed the wrong class name, I have fixed this now.
_TransmissionDataSerializer is now a "private" class to be used by the
TransmissionDataSerializer.loads and TransmissionDataSerializer.dumps
which are going to be abstractions from the JSON module so that
serialization is simple.
Added the custom loads and dumps

The custom loads and dumps have been implemented and tested.

These functions will act as an abstraction to the built in JSON module.
They are specialized for TransmissionData serializing and deserializing.
Tests are passing right now, this should be working ^_^