MOTECH-1369 Fix randomly failing MessageCampaignBundleIT

I believe the issue here was the ordering of the tests
and the fact that HttpClient somehow remembers the
proper credentails, even thhough they are cleared.
I remove cookies after each test in hope that this will
solve the issue.

Change-Id: I9c8269f837d721b08b9994e17c7ad76f6d348164