Update softclipping for chipseq (#3476)
Update softclipping for chipseq (#3476)

in chip-seq, for bowtie2, we changed '--very-sensitive' -> '--very-sensitive-local' to softclip.
This has been discussed with Rory and Meeta.
We can wait for Shannan to confirm this change.
lbeltrame/bcbio-nextgen,lbeltrame/bcbio-nextgen,lbeltrame/bcbio-nextgen