Gracefully handle unknown keyword arguments to Property()

Previously, this would raise:

    ======================================================================
    ERROR: test_unknown_kwarg (test_property.TestProperties)
    ----------------------------------------------------------------------
    Traceback (most recent call last):
      File "../normalize/tests/test_property.py", line 474, in test_unknown_kwarg
        Property(yo_momma="so fat, when she sits around the house, "
      File ".../normalize/property/meta.py", line 213, in _has
        return has(selfie[0], self, args, mixed_kwargs)
      File ".../normalize/property/meta.py", line 74, in has
        extra_traits.update(list(implies_traits)[0])
    IndexError: list index out of range

Handle & gracefully explain the usage error.
Merge branch 'maint'
Don't neglect collection item NO_CHANGE Diff's with fuzzy match

The fuzzy match code can actually result in no net differences, even if the
items did not exactly match the first time around.  Check for and emit them
if options.unchanged is selected.
Release Engineering for 0.6.1