Problem: test_create_dip.py test may fail because of DST

[jrwdunham]

I'm getting a failure at https://github.com/artefactual/automation-tools/blob/master/tests/test_create_dip.py#L143 when I run test_create_dip_success locally:

>               assert aip_lastmodified - 1 <= lastmodified <= aip_lastmodified + 1
E               AssertionError: assert 1510853052 <= (1510849451 + 1)

This looks like a (DST) timezone issue because the dates are off by 1 hour (plus the expected 1 second):

• 1510849451 is 2017-11-16 08:24:11
• 1510853052 is 2017-11-16 09:24:12