Since I9d3bafa075631a3f48cbd3627a4cc1a5a859cce2 in rally, platform
should be part of context name (context@platform).
Otherwise, a warning message (or even breakage because of
I10ac687f9f420dcf0d907b51d5d9303f68d35719) may be triggered.
*) Rename rally-scenarios that is quite misleading to rally-jobs.
rally-jobs makes much more sense, cause it actually contains files
related to rally job
*) Update rally-jobs/README.rst to add more info
*) Update rally-jobs/plugins/README.rst to expaling plugins
*) Add new directory rally-jobs/extra, this directory is copy pasted
in gates and can be used for files that are required by some of