Have transfer begin / end as time_t. #6885
Have transfer begin / end as time_t. #6885

The beginning and end of transfers should be done in seconds in order
to preserve accuracy.  Total time elapsed should be the only thing kept
in double-accuracy.

htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor