java: simplify version checks to only use PATH
java: simplify version checks to only use PATH

Thanks to @bwubb:
https://groups.google.com/forum/#!topic/biovalidation/NskVZlJrcTk

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