Remove unused db_sync from extensions

The db_sync in the extensions isn't used, either by the tests or
by keystone-manage db_sync, so remove them.

Change-Id: Ia0598e8dae81e258a05767f47525d5c11acce8db
Keystone doesn't use pam

The requirements.txt file had pam, but Keystone doesn't use pam.

Change-Id: Ib617146d4ec75532f994ae85837ecbf383647306
Sync from oslo db.sqlalchemy.migration

Sync the updated migration module to prevent errors on non-utf8
migrate_version and alembic_version tables (not controlled by the
schema migration directory).

Change from oslo commits:
[2fd457bf2cc] Ignore migrate versioning tables in utf8 sanity check

Change-Id: I6aef126b8d09c7a44f3815c4143ef1d4e5463426
Closes-Bug: #1301036
Merge "Remove unused db_sync from extensions"
Fix parallel unit tests keystoneclient partial checkout

The unit tests were failing with an error that keystoneclient
didn't have some modules (usually v2_0). This was because the
tests were running in separate workers when they should have been
running in a single worker to ensure that the checkout was done by
a single worker.

Change-Id: I33262dd82aaebe8e0ff0f9faf5c5612efb20f551
Closes-Bug: #1301664
Merge "Keystone doesn't use pam"
Merge "Sync from oslo db.sqlalchemy.migration"
Merge "Fix parallel unit tests keystoneclient partial checkout"