* bus/driver.c, bus/services.c, bus/services.h: Add a ReleaseName
	method to org.freedesktop.DBus to release a bus name or give up
	waiting in the queue for it.

	* dbus/dbus-bus.c, dbus/dbus-bus.h, dbus/dbus-shared.h: Add a
	dbus_bus_release_name method to send the ReleaseName method calls.
	Add constants for the return values to dbus/dbus-shared.h.

	* doc/dbus-specification.xml: Document the new ReleaseName method
	in the specification.

	* python/dbus_bindings.pyx: Add a low-level python binding for the
	release name method.

	* python/exceptions.py, python/service.py: Make freeing BusName
	objects release the name. Add a NameExistsException, and fix a
	bug with creating UnknownMethodException.

	* test/python/test-client.py: Add tests for freeing BusName
	objects causing names to be released.