Use screen for connecting to serial ports for xmodem

At least until we verify the patch to add xmodem to cu works
Use Django's recommendation and start with randomized seeds.
Do a scrub after installation / upgrade.
Stupid me.  Thanks Suraj.
extra protection
RID should be the default backend
Until SSL works, don't show the field
Until SSL is working, don't display the certificate either
Merge remote-tracking branch 'origin/master' into freebsd10