Merge pull request #1 from lomereiter/master

update sambamba to v0.4.3
Add builds for freebayes associated tools from GitHub revisions: vcflib and glia. chapmanb/bcbio-nextgen#204
Ensure homebrew prefix included in glia build INCLUDES to correctly find google sparsehash install. chapmanb/bcbio-nextgen#206
add sambamba mac os x build