fixed bugs, changed imports around.

plex/__init__.py
- no longer imports from other files.
- you must now manually specifiy what you want to import from the modules directly.

plex/media.py
- new function plex_media_object_batch
   - accepts multiple keys, does batch requests to server and returns multiple objects.
- fixed bug in plex_media_object when accepting both 'key' and 'xml' arguments

tool-check-plexdb.py
- fixed imports

tool-toggle-gz.py
- fixed imports