rally need to be setup as part of contrail testbed setup

[Harish Kumar]

Plan is to use rally for performance testing and benchmarking. So rally need to be setup on one of the node as part of contrail testbed setup.

[OpenContrail Admin (ci-admin-f)]

Review in progress for https://review.opencontrail.org/15762
Submitter: Harish Kumar (<email address hidden>)

[OpenContrail Admin (ci-admin-f)]

Reviewed: https://review.opencontrail.org/15762
Committed: http://github.org/Juniper/contrail-fabric-utils/commit/d78c9e68a1dadeae7a127312829b3b62935cd41d
Submitter: Zuul
Branch: master

commit d78c9e68a1dadeae7a127312829b3b62935cd41d
Author: hkumarmk <email address hidden>
Date: Fri Dec 11 11:29:53 2015 +0530

Install and setup rally

This patch:

* Install rally from git source in the node with rally role
* git source and branch can be customized with testbed configuration
* Use sqlite as database - currently one rally per contrail setup
* Setup rally with current openstack cloud deployment
* Added example configurations on testbeds
* provide a way to run rally with custom or default scenario
configuration

One can use
* fab install_rally to install rally on rally node
* fab setup_rally to setup rally with current openstack cluster
* fab run_rally to run rally - either with a custom task argument yaml
file or default arguments provided in testbed.py file.

Fixes-Bug: #1525083
Change-Id: Icdf82d40a2f51f9e6907c7964c74e9dd15108919