Update rampConfig key when stopping ramps.

At the start of each ramps, the hxActor generates a keyword describing the ramp: rampConfig=visit,ngroup,nreset,nread,ndrop. And at the end of each completed read, the hxActor generates a keyword indicating that: hxread=rampNum,groupNum,readNum

Now that we can stop ramps, we need to update the rampConfig key so that the GUI knows how many reads are in the ramp.