Port Rickshaw engine code from shell scripts (bash) to Python

[k-rister]

This will allow for higher levels of functionality as well as better native handling of JSON which is how almost all of our configuration data is managed.

[rafaelfolco]

what is tthe scope of this change ?
https://github.com/perftool-incubator/rickshaw/blob/master/engine/engine-script and
https://github.com/perftool-incubator/rickshaw/blob/master/engine/engine-script-library ?

does it imply in modifying rickshaw-run (perl)?
Thanks

[k-rister]

This is just the engine code that you linked to -- this has nothing directly to do with rickshaw-run.