Bump alembic to 0.6.4 for Neutron

Recently merged neutron healing migration
(https://review.openstack.org/#/c/96438/)
needs alembic >= 0.6.4 for mysql.

The relevant fix in alembic:
    https://bitbucket.org/zzzeek/alembic/commits/b29780719904

Change-Id: If67241592ba82aed3b41b4acec17bd8d604a3c4b
Partial-Bug: #1342507
Explicitly states the keystonemiddleware version

Currently, there is no version listed. However, there exists a page for
version 0 of the library in pypi.

https://pypi.python.org/pypi/keystonemiddleware/0

This change states the version of the library to "greater than equal"
1.0.0 which is the first real version of the same.

Change-Id: I2bbee6db56e166387d34a4655996a85db9b64ad3
Merge "Bump alembic to 0.6.4 for Neutron"
Merge "Explicitly states the keystonemiddleware version"