Completely decouple fuse-dependent stuff from nfspy
New .gitignore
Fix bug in NFSError.__str__()
New non-fuse interface: nfspysh

`nfspysh` provides a vaguely ftp-like interface for using NfSpy. This
should work for systems that do not have FUSE libraries (e.g. Mac OS X
and Windows)
Update setup.py to install nfspysh