Python 3 compatibility: subprocess system calls for schedulers
Python 3 compatibility: subprocess system calls for schedulers

Ensures decoding of bytes to strings for subprocess calls to get
scheduler information. Fixes #2742

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