Revert "added flag "velvet""

This reverts commit 179a5412808c442b390232fd70c995b311330bbc.
Fixes #17.
Fixes #23

Quits if a contig contains both the beginning and end of the target if
the -complete flag is specified; otherwise reports contigs that contain
both the start and end of the target at the end.
First pass at implementing strand information

This calculation, based on the best hit for tblastx, is not quite right.
velvet flag uses intermediate blast results from past runs
Merge branch 'master' into velvet