Implement SCP communication with Axiomtek boards

[christophkern]

As far as I know, we are still using the insecure ftp protocol for communication with our instruments in the field. This has caused some problems for us, as ftp comms are not allowed on some network connections, particularly those that go over the public internet (as some of our connections in Alaska do). The work around has been to write manual scripts for secure data transfer to bring data to the observatory, then use the directory polling feature of the NOVAC program to detect and evaluate new data. But this is cumbersome at best. Also, the new Axiomtek boards do not support ftp by default. We are trying to see if we can get it working, but a better solution would be to switch to SCP altogether.