snglinspiraltable.c: Name COMPLEX8TimeSeries "snr" instead of

"*1_snr", matching what was done pre-itacac

inspiral.py: Create sub-threshold trigger to add to gracedb uploads if
we have snr from an instrument that didn't produce a trigger above peak
coincident with the candidate in question. Also, only upload one snr
time series per trigger (including the sub-threshold trigger), not an
snr time series for each ifo for each trigger. After this patch, gracedb
uploads should look almost identical to what they were before switching
to itacac