Linting: error for somatic/germline with no tumor
Linting: error for somatic/germline with no tumor

Provides a useful error message when configuration specifies somatic
and germline callers but doesn't have a tumor sample to run these.

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