removed GSL prerequisite from lumpy. also, updated README.md to use sambamba 0.4.6 (deals with empty bams gracefully)
removed GSL prerequisite from lumpy. also, updated README.md to use sambamba 0.4.6 (deals with empty bams gracefully)

PiaEP/speedseq,s-boardman/speedseq,pombredanne/speedseq,pfxuan/speedseq,pombredanne/speedseq,pombredanne/speedseq,s-boardman/speedseq,PiaEP/speedseq,hall-lab/speedseq,hall-lab/speedseq,pombredanne/speedseq,hall-lab/speedseq,PiaEP/speedseq,pfxuan/speedseq,s-boardman/speedseq,pfxuan/speedseq,pfxuan/speedseq,pombredanne/speedseq,s-boardman/speedseq,pombredanne/speedseq,PiaEP/speedseq,PiaEP/speedseq,PiaEP/speedseq,pfxuan/speedseq,s-boardman/speedseq,hall-lab/speedseq,s-boardman/speedseq,pfxuan/speedseq,hall-lab/speedseq,hall-lab/speedseq