[evlatests] S band test files

[Ken Sowinski]

I have created a maintenance script, Sband; and an operations
script, Ssysstart.evla; both in the usual places.  Both use
the default frequecies from the database which I have chosen
to be 3000 and 3050 MHz.  Let me know if there is any problem
trying to use these scripts.

Dan assures me that this choice is likely to be free of
serious interference.  His list of frequencies to avoid
includes 2.3 to 2.8 GHz and 3.4 to 4.0 GHz.