Delete/Update All with Joins

[jazzyb]

See the note at the bottom of the tests:

    # NOTE:  The assertions commented out below represent how joins *could* be
    # handled in SQLite to produce the same effect.  Evenually, joins should
    # be converted to the below output.  Until then, joins should raise
    # exceptions.

[jazzyb]

Similarly, can we do something similar with updates?