Due to some issues with bundler vendoring (https://github.com/carlhuda/bundler/issues/2039),
I've changed the method of listing files in the gem so that it doesn't call a git subprocess.
Removed unneeded test_files and executables declarations, since those aren't needed in the
installed product.
Merge pull request #7 from jasiek/master

I've changed the method of listing files in the gem so that it doesn't call a git subprocess.