Preliminary support for stacked movies

Related files might not be cleaned correctly and the number of movies cleaned will increment for each part instead of each movie.
Attempt to fix amount of stacked movies cleaned
No longer do an entire run for each part of a stack

Each part of the stack is now deleted right away, and both the delete and delete_empty_folders methods can now handle stacked paths.
Moved stripping of stack volumes to separate method

This will allow you to find the common file name in a list of files that are part of the same stack, minus the _part1, _dvd1, etc.  and the extension.
Support for moving of stacked movies
Moved cleaning of related files to its own method

This method now handles both deleting and moving of related files based on the user's settings.
Optimize imports and docstrings
Merge branch 'stacked_movies'. Closes #19.

Conflicts:
	default.py
Fixed logging for stacked movies. Closes #19.
Upgraded to the new PO translation system. Closes #9.