Qualimap should use bed/gff file for exome qc

... And I removed the options of automatically pointing to
TruSeq/SureSelect as it might lead to a false seens of security for
picking the correct files, while in reality one is using a outdated
version of the target region.
Correct usage message
Making interval file optional argurment...

... for qualimap.
Merge branch 'work_on_exome_wf' into devel
Bumping version to v1.2.0-beta15