Adding support for GlobalCache itach flex network serial port

[jondthompson]

Just providing a heads up that I'm starting work on providing support for the iTach Flex network serial port. I know I could replace it with a raspberry pi easier, but that would break the existing app my family has on their phones to control it (we don't even have the keypads installed).

Since the new model has a built in ethernet jack (that appears to be serial to TCP) this will also open the possibility to supporting them in the future (although tests of the free app shows that it's not the same protocol directly)