Top-level directories can't be used as share paths

[wmcbrine]

Mainly an issue on Windows (with its multiple "drives"), but you can see it on any OS by setting the path to "/".

[wmcbrine]

This is tied in with the way pyTivo doesn't include the top-level "/" in the paths it sends to the TiVo. I've made three or four attempts to fix these issues, separately and together. I got it working for music and photo, but the video plugin is problematic.