provision: Send 'update schema now' action after each schema modify operation

This commands reloads the schema information into the server cache.

(cherry picked from commit f4fbaad30ebc2d910efea1eb281ffbc1be687378)
provision: Send 'update schema now' in provision_schema function

Instead of calling modify_schema function explicitly, do it inside the
provision_schema function. This way it reduces the verbosity on command output
and is integrated inside the ldb transaction.

(cherry picked from commit c3c61d1ec42bce900e283eb0cc1f3ce20f4b0543)

Conflicts:
	python/openchange/provision.py