[YABI-456] metavelvet requires directory as input

[ccgbuildbot]

[reporter="jmccooke", created="Thu, 13 Mar 2014 16:43:38 +0800"]

Metavelvet examines the output from velvetg to determine and isolate contigs origination from different genomes. The tool takes the output of velvetg in the form of a directory as input. I require some means (a wrapper??) for being able to select a directory as an input for this tool.