Pin bedtools to previous version to avoid build errors on 2.18.0 (arq5x/bedtools2#3). chapmanb/bcbio-nextgen#220 chapmanb/bcbio-nextgen#219
Revert to samtools 0.1.19, installing version without conflicting bcftools. Fixes chapmanb/bcbio-nextgen#221
Ensure tabix installed to provide bgzip without samtools 0.2.0