vcfanno: fix for pre-specified gemini inputs
vcfanno: fix for pre-specified gemini inputs

Ensure we pass the correct data_basepath when config contains gemini inputs:
```
vcfanno: [gemini]
```
Thanks to @ohofmann, @vladsaveliev

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