Added more implementation code to the serials comms, mostly API level and Flow Control. It is getting close to the first test build.

Signed-off-by: Wynand Marais
Finished the first build of the SerialComms library. Started the first of the unit testing.

Signed-off-by: Wynand Marais <wmarais@wynand.marais@gmail.com>
The first unit test is partially working. Acknowledgments doesn't appear to be working however.

Signed-off-by: Wynand Marais