feature idea: add originate

[philipvh]

Currently one can process events resulting from a dial action inside asterisk. But there is no node to originate a call as result of some flow action.

As work around one can originate a call by activating a http request POST node with the ari credentials and msg.url properly set so that it activates the asterisk originate, but this is less elegant.

Adding an originate node would make the function complete