Add rake tasks to manage indices, pipelines and models

[esmarkowski]

rake stretchy:status Show status of all indices, pipelines, ml models, etc

rake stretchy:up Registers and deploys all ML models, pipelines and indices

rake stretchy:down Underplays and deletes all ML models, pipelines and indices

rake stretchy:index:create Creates all stretchy model indices, creates dependent pipelines and registers and deploys ml models

Pipelines and dependents are created as dependency hooks

rake stretchy:index:create MODEL=MyModel Create individual index and dependents

rake stretchy:index:delete Undeploys all ml models, removes indices

rake stretchy:index:mapping Show mappings

rake stretchy:pipeline:create Creates all pipelines and their dependent ml models

rake stretchy:pipeline:create PIPELINE=MyPipeline

rake stretchy:pipeline:delete Undeploys dependent ml models and deletes pipelines

rake stretchy:ml:model:create Registers and deploys ml model

rake stretchy:ml:model:register Registers ml model

rake stretchy:ml:model:unregister Unregisters ml model

rake stretchy:ml:model:deploy Deploys ml model

rake stretchy:ml:model:undeploy Undeploys ml model