remove flake8-import-order for test requirements

- When flake8-import-order is installed the additional
  ordering tests it provides are enabled by default.
- When devstack installs python projects from source
  such as nova, the pip_install function installs both the
  requirements.txt and test-requiremets.txt dependencies systemwide.
  As a result, any python project that runs pep8 tests without a
  python virtual environment will also have import ordering enforced
  which may fail.
- This change removes flake8-import-order from the
  test-requirements.txt to prevent failures in projects other
  than nova that don't enforce pep8 import ordering.

Change-Id: I994df178f0000a0840f6658ccc2f277d5503f826

test-requirements.txt

@@ -6,7 +6,6 @@ hacking!=0.13.0,<0.14,>=0.12.0 # Apache-2.0
 coverage>=4.0 # Apache-2.0
 ddt>=1.0.1 # MIT
 fixtures>=3.0.0 # Apache-2.0/BSD
-flake8-import-order==0.11 # LGPLv3
 mock>=2.0 # BSD
 mox3!=0.19.0,>=0.7.0 # Apache-2.0
 psycopg2>=2.5 # LGPL/ZPL

tox.ini

@@ -37,6 +37,8 @@ commands =
 
 [testenv:pep8]
 basepython = python2.7
+deps = {[testenv]deps}
+  flake8-import-order==0.11
 commands =
   bash tools/flake8wrap.sh {posargs}
   # Check that all included JSON files are valid JSON