add collector definition to swagger.yaml (#423)
add collector definition to swagger.yaml (#423)

* initial commit

* amend as per Ians comments

* change KILL to STOP command

* change some commands to be executable by refocus collector only

* amend as per Ians and Shrirams comment

* revert the status code of heartbeat to 200

salesforce/refocus,salesforce/refocus,salesforce/refocus