vcfanno: back compatibility for build 37 gemini
vcfanno: back compatibility for build 37 gemini

Supports GEMINI supplied configuration files with correctly setting
the basepath. Thanks to @ohofmann

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