[evlatests] VLA sawtooth phase

[Barry Clark]

I think I have maybe fixed this.  Phases are currently pretty horrible,
but I think they are not showing a 10 second pattern.  But it's pretty
hard to tell from the D10 display.  Rick, you might have a look at the 
data between 21h22 and 21h32 today, and see what shows up.

Just for kicks, I ran from about 21h37 to 21h45 with the sign of the
chirp reversed for EVLA antennas.  Does seem to convert that into a 
sawtooth.  Is it a straight sawtooth?