Test message delete when claim expires

The patch adds a test for message deletion after a claim has expired.
The result of the test is that the message should be deleted.

Unfortunately, some issues related to the state of the sqlalchemy driver
make it quite hard for this test to work there without further changes.
I'm proposing this patch with some skips in place for the scenarios
where sqlalchemy is required, I'll propose a follow up patch to fix
those issues and enable these tests.

Closes-bug: #1369536

Change-Id: Icb12eed18c37455ad3528fa6a84fb8f2d8fcf19f
Add rally job related files

* Add README.rst file with useful description
* Add extra and plugins directory with corresponding README files
* Add rally task designate.yaml that will be actually run in gates

Infra related patch is here:
https://review.openstack.org/#/c/135132/

Change-Id: Ida3c3aa24f63592f9c4bd7143d30377fddd021a6
Merge "Add rally job related files"
Rename rally-scenarios/ to rally-jobs/

rally-scenarios is quite strange name for files related to rally jobs.
So rename it to something more reasonable

Change-Id: I4909890fd97ce3bae809c28a28bdda7a4cfdd79d
Merge "Test message delete when claim expires"
Document mongodb's driver deployments

This patch adds a base documentation for mongodb's driver. This
documentation is useful for both users, developers and operators, and it
should be probably moved to the users-guide.

Lets work and brainstorm on it as a developers doc first and then move
it.

Change-Id: I532c3d5edf20497eb9eae1f691dd706c5fe10b2a
Replace sqlite with sqlalchemy

We used to have an sqlite driver and we kept it as the default value for
our storage drivers to keep backwards compatibility. It is now time to
move forward and use sqlalchemy instead.

Note that the entry points in setup.cfg are kept because we need them to
load the proper driver from pools based on the connection uri scheme.

Change-Id: I527c6ab15cc36e69d49a57a916ebc1296f73e3ce
Merge "Replace sqlite with sqlalchemy"
All-in-one patch for notification service

Change-Id: I0d1518b6a98804c48f4a1b07d40ed5828cb125aa
Merge the routes of notifications into queues

Change-Id: I8bdffc72ad9765ce08a9e7c1d9c66987a34a466a