Control command refactor

In the framework of https://github.com/TauLabs/TauLabs/issues/743, this implements the first phase, which is to split the UAVOs. There is no added functionality or UAVO fields. This will come in the second phase.

In theory, since there are no duplicate fields it should be impossible to send or fetch data from the wrong UAVO. However, this should be double-checked, since it touches a lot of critical components.

Untested.