Prepare samples: skip empty input lines Fixes #1625
Prepare samples: skip empty input lines Fixes #1625

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