Extra scripts with DevStack support

DevStack project don't merge support of stackforge projects into master.
There is an alternative support to use the devstack infrastructure. The
mechanism based on ability of implementing hooks such as extras.d.

Implemented functionality of the Rally library:
* Install Rally from repository
* Configure Rally and create database tables
* Create a special tenant
* Optionally add devstack installation as a deployment

blueprint rally-devstack-extras

Change-Id: I43b74db203ca385d321ba9d6f79c2bd21f947e13
Remove results before a task

Results should be removed before a task into a transaction otherwise the
deletion doesn't happen with error because Foreign Constraint
verification failed.

Closes-Bug: #1269866

Change-Id: I2cf2087ea5f9badba6540a5a5430650a30d51162
Refactor unit tests for dummy engine

This patch removes a duplicate test from TestDummyDeployEngine and also
renames/reorders several test methods to make the code more consistent.

Blueprint unit-tests-refactoring

Change-Id: Icdd97d3242a43d276f51ae2681969ffae747040b
Print deployment id when a deployment is created

Change-Id: I13db9c87031cecaadfef7a42d17d713749a6fde0
trello: https://trello.com/c/hURll2Id
Merge "Extra scripts with DevStack support"
Merge "Print deployment id when a deployment is created"
Merge "Refactor unit tests for dummy engine"
Benchmark scenarios for Rally: run task in instance

This patch allows a user to define a scenario where Nova instances are
created, then a script which outputs arbitrary JSON is run, and then the
instance is destroyed.

This allows tests/benchmarks from the instance perspective, as well as
from OS APIs.

blueprint benchmark-scenarios

Change-Id: I4b1f77f5f8c55fe1da41b6ab0b23eb03303ba95f