Clean up processing time variables

[yzhang104]

convert to hh:mm (or h:mm) format:
fas1

delete the following variables:

fas10a Processing start time for ethylenediaminetetraacetic acid (EDTA)
fas10b Processing start time for serum.
fas5 Time at start of venipuncture
fas6 Elapsed time until tourniquet released
fas7 Time at end of venipuncture.