friendly TZ name is not always handled correctly

[treyd]

This test fails:

    timestampTZ = '10/24/12 EDT 15:54:42.000000'
    timeformatTZ = '%m/%d/%y %Z %H:%M:%S.%f'

    assertTrue(keywords.timestamps_should_be_equal(timestampTZ, timestampTZ, format1=timeformatTZ))

From what I can tell, this is because dateutil can't handle the timezone friendly name in the string. dateutil supposedly lets you set up a dict of friendly names to offsets, but its curious why there isn't a default list being used. will have to investigate further into dateutil...