Removing pep8/flake reqs in test-reqs

Currently getting version mismatch on Travis tests.
MANY flake8 error fixes, all cosmetic
Many additional flake8 syntax fixes

More were found in the py26 env
And yet more flake8 fixes

Mostly import alphabetical order errors and space after multiline doc
Adding back # noqa to quota_driver import
And yet moar flake8 fixes
Last few flake8 changes, only H202s remain
Adding temporary # noqa to assertRaises

We need to go back and address this, by adding more specific exceptions to
the base code (i.e. the tests are not the problem). However, this is a hard
blocker currently, so putting it on the backburner for now.
Merge pull request #149 from insequent/pep8andflakefixes

Removing pep8/flake reqs in test-reqs
Fixes alembic migrations for RM6804

* Absorbs 56* revision (subnet_id, address unique constraint) into
  18* (initial revision); oblige already contained the changes in
  56* and prod databases were stamped to 18* so it makes sense to
  absorb contents of 56* into 18*.

* MacAddress.address is already a primary key; removes
  UniqueConstraint on (mac_address_range_id, address) from model.

* Removes added MacAddress unique constraint from 43* revision.