[software/adc_noisecal_delays.py] adding file to automatically find adc delays given then noise box

The adc_noisecal_delays.py script will work only for sites with
the 4-way switch.  It should be run after VDIF_test.py and will
automatically find and compensate for delays between the two ADC
boards on a single R2DBE.

It does this by:
 [*] setting the switch to noise,
 [*] grabbing the 8-bit data from the R2DBE on-chip BRAM,
 [*] correlating this data to find the delay,
 [*] saving delay v lag plot to oper's home dir (cross_lags.pdf),
 [*] writing to the correct register on the R2DBE to compensate,
 [*] taking more data
 [*] saving delay v lag plot to oper's home dir
     (cross_lags_fixed.pdf)
 [*] set switch back to IF

this protects the operator and the experiment by removing any
accident that the noise switch be left to noise during an
experiment