Update the keyring dependency

Keyring is now at version 3.6 so it seems like
we should be ok moving to a newer version and
removing the need to continue supporting the
older versions.

Also the existing requirement doesn't seem to
make logical sense. It doesn't seem that this
restriction '>=1.6.1,<2.0,>=2.1' should ever
match anything.

Change-Id: I711092bfab97190de635a099fb0e771a22e90197
Upgrades Pbr to exclude 0.7 due to Windows issue

Pbr 0.7 fails on Windows generating a blocking issue:
https://bugs.launchpad.net/pbr/+bug/1294246

Change-Id: Ieab4bf32b04ee080d8447e12e92dc47508f87083
Raise oslo.messaging to 1.3.0

We prefer released versions to be required.

Change-Id: Ifafbae3dfbc27f5ac2005051dbfc73d134a0a57a
Taskflow 0.2 released

Taskflow 0.2 has released and should work with all
existing openstack projects as-is (integrating gating
has verified this) so unbinding and resetting the bound
at 0.3 (which does not exist yet).

Change-Id: I1e6f782c5cc6e9c54be0efc089f2876357240ac7
Merge "Taskflow 0.2 released"
Merge "Update the keyring dependency"
Merge "Upgrades Pbr to exclude 0.7 due to Windows issue"