GCD files for Pass3 Step 2

[gh999ic]

Step 2 = PFFilt to Offline

[gh999ic]

Cannot find button to create sub-issues, seems it's a new feature :(

SPE corrections - Spencer et al
IceTop SLC calibration constants into gcdserver DB - Kath
IceTop VEMCal constants into gcdserver DB - Kath
good run start and stop times into GCD files for seasons <2013 (only?)

Both of Kath's issues require PFFilt files as input