Make test mysql connection code less confusing

There are two similar methods used for connecting to MySQL apps, but
their arguments differed in order which made for some confusion. This
makes their argument signatures identical.

Change-Id: I48818e2eadb81944e7369e12d09af9c3394d6b57
adding configuration group support

This allows users to make custom configurations groups and apply them to
multiple instances. Configuration parameters that can be set are listed
in the validation_rules.json file.

implements blueprint configuration-management

Change-Id: I99b0bfe51c131ace30774e75e30d620101ed2e0b
Adding override.config.template for percona

After the 'adding configuration group support' patch was merged,
percona instance-create is failing because the TM cannot find
the override.config.template for percona. Adding this template
fixes the problem.

Change-Id: I63404cfa8cd9bd850e4fc7457a3d4bcc2711685c
Closes-Bug: #1277376
Ignore outdated messages sent to conductor

Adds a sent_at field to conductor messages in the manager so that
messages that get out of sync on their way to conductor don't cause
trouble by updating instances or backups with out-of-date information.

Implements: blueprint conductor-ignore-old-messages
Change-Id: If06d2f9c9f993100be66f71274240a59b05b66e3
Merge "Make test mysql connection code less confusing"
Adding additional datastore tests

This adds 4 more datastore types and versions tests.

Change-Id: I4da3721a764d76e1bd625da69fdef3976edb64d7
Modifying tests to run with different configurations

Updated datastore tests to make datastore configurable and not
assume that 'mysql' datastore will always exist.

Fixed test_create_with_bad_availability_zone. Before it was
giving a false positive. Now it is testing the right thing.

Change-Id: Ie4e81e173b73302b40e521e4a41569404203b9d2
Closes-Bug: #1276346
Merge "Ignore outdated messages sent to conductor"
Merge "Adding additional datastore tests"
Merge "Modifying tests to run with different configurations"
Initial support for single instance Cassandra Database

Reasons
- This code adds ability to create/delete instance
with mongodb service type. No other operations supported.
- Trove should support multiple extensions. One of the is NoSQL support.
Main goal is to add support for Apache Cassandra NoSQL database.

Changes
This code gives ability to create/delete instance
with cassandra datastire type. No other operations supported.

Change-Id: Ib48f6392765af49c2df1447c3df46675825d210f
Implements: blueprint cassandra-db-support