----

kirr: factor running `zodb ...` into zodbrun + add test for `zodb -h`.

Added test currently passes on py2, but fails on py3:

	out = <_io.TextIOWrapper encoding='UTF-8'>

	    def usage(out):
	        print("""\
	    Zodb is a tool for managing ZODB databases.

	    Usage:

	        zodb command [arguments]

	    The commands are:
	    """, file=out)

	        cmdv = command_dict.keys()
	>       cmdv.sort()
	E       AttributeError: 'dict_keys' object has no attribute 'sort'

	zodbtools/zodb.py:55: AttributeError

It will be fixed in the next patch.