Xd 1517

This PR addresses XD-1517 (removing _deployments URL) by providing separate endpoints /deployments  and /definitions for streams and jobs. Some related changes are:

(also applies to Jobs)
deploy is a POST to /streams/deployments  instead of a PUT to /streams/{name}?deploy=true
undeploy is a DELETE /streams/deployments/{name} instead of PUT /streams/{name}?deploy=false
undeploy all is DELETE /streams/deployments
But if the "resource" in this case is the deployment instance for the stream whose name is provided in the path, that doesn't exist yet. POSTing to /streams/deployments/foo is creating a new resource: the deployment instance for stream foo