removed --fields flag support from vep args and supporting functions
removed --fields flag support from vep args and supporting functions

vladsaveliev/bcbio-nextgen,biocyberman/bcbio-nextgen,lbeltrame/bcbio-nextgen,lbeltrame/bcbio-nextgen,a113n/bcbio-nextgen,chapmanb/bcbio-nextgen,a113n/bcbio-nextgen,chapmanb/bcbio-nextgen,biocyberman/bcbio-nextgen,vladsaveliev/bcbio-nextgen,chapmanb/bcbio-nextgen,biocyberman/bcbio-nextgen,a113n/bcbio-nextgen,vladsaveliev/bcbio-nextgen,lbeltrame/bcbio-nextgen