change descriptor.json format and add descriptor for action.

[abramvandergeest]

Last week we decided that the descriptor.json format for the operation was un-used and redundant. I am trying to determine what the new descriptor.json needs to look like. I think we decided that it should include spec version.

@fm-tibco @mellistibco @skothari-tibco - what did we want the descriptor to look like.

relatedly we were also going to look at adding a descriptor to the action. it was mentioned that we should do something like the flogo-flow descriptor. Can someone point me towards this json? I couldn't immediately find it.