Merge Sebastian Spaeth's python bindings into bindings/python

Sebastian offered to maintain these bindings within the notmuch
repository and offered them in the following repository:

	git://github.com/spaetz/python-notmuch.git

These are the bindings formerly known as "cnotmuch" and now known
simply as "notmuch" from within python.

The bindings are not yet integrated into the build system and
packaging of the primary ntomuch repository.