Gui improvements
set wrapped call to shell=True
switched hard coding /usr/bin to /usr/bin/env for cross platform
compatability
Restored the ability to open more than one program requiring the same
mount path at the same time
Properly raises an error if target directory is not already mounted, and
is not empty
Moved to distuitls for distribution

*fixed displayed help info
small change to README.rst to keep usage text consistent