Switch single-cell test to use Rapmap.
Switch single-cell test to use Rapmap.

kallisto support works but requires a manual intervention to get
going.

Addresses an issue in #1524.

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