restrict requests version with !=2.4.0

Related-Bug in requests:
https://github.com/kennethreitz/requests/issues/2192

Related-Bug: #1363979

Change-Id: I711f5e5fdaa17e22bad075b3f22a6c199dc255dc
add header warning against sorting requirements

During sync, add a header to the requirements files warning anyone
against changing the order of the contents, especially against sorting.

Addresses-Bug: #1365061
Change-Id: I64ae9191863564e278a35d42ec9cd743a233028e
Rally needs bumping python-novaclient

python-novaclient <= 2.17 doesn't support authentification via
auth_token (at least without specifing username and password)

Which was changed here:
https://review.openstack.org/#/c/85920/

So it makes sense to bump version of novaclient

Change-Id: I6d2a0a414b89e757a48d6616c8e74ed34591d02b
Merge "restrict requests version with !=2.4.0"
Merge "add header warning against sorting requirements"
Bump up taskflow to its newest version

Taskflow 0.4 was just released so update the bounds
to be the version that is most useful for the juno
release.

Release notes @

https://etherpad.openstack.org/p/TaskFlow-0.4

Change-Id: Ib261d3d3defdb0fa396b0cef16b322bcce00c64d
Merge "Rally needs bumping python-novaclient"
block sqlalchemy migrate 0.9.2 as it breaks all of nova

Closes-Bug: #1368391

Change-Id: Idbe75bc768d91dd1a807d9cf90d82afa0909594e
Merge "Bump up taskflow to its newest version"
Merge branch 'master' into csr1kv_for_routing_juno