TPG366 Agent improvements

[BrianJKoopman]

While working on #1066 there were a few things I noted could be improved that I wanted to capture in an issue:

• We could drop the dependence on numpy in the drivers, we don't really need it here.
• The gauge power/status could be added from the PRX output -- this was something that was originally of interest, but was being queried separately. I believe the PRX command already outputs what was wanted though.
• Query output should be put into a session.data object.