renamed sweep-reads-buffered to sweep-reads
removed SHELL= once again
Fixed --outdir when using --label-by-group in sweep-reads-buffered
Merge branch 'master' of github.com:ged-lab/khmer into fixes/sweep-reads
Merge branch 'fixes/sweep-reads' into cs/sweepfix
minor cleanup on sweep-files: shebang and make db req'd argument