Merge branch 'dhcroft-setVelopT' into '2016-patches'

Make the setting of the sign of pT of Velo only tracks deterministic

Added code to set the pT of the VELO only tracks with a sign based on the first strip in the first cluster rather than the track key (which was random). Also an option to reverse the sign for mag up/mag down MC comparisons. (TrackTools/src/TrackStateInitTool, TrackUtils/src/TrackPrepareForFit, TrackUtils/src/TrackPrepareVelo)

See discussion in LHCBPS-1547

See merge request !85 (merged)

Contrary to what was thought at the time of MR !133 (merged), we decided to include this in the next release since both HLT1 and HLT2 will be updated