Improve error message on disconnected websocket
Log sbt connection time and reword a couple messages

Trying to make it a little clearer when we connect/disconnect.
Merge pull request #715 from typesafehub/wip/havocp-disconnect-error

Improve error message on disconnected websocket
Merge pull request #716 from typesafehub/wip/havocp-connect-times

Log sbt connection time and reword a couple messages
Bump to sbt-remote-control dde8acfb1ef78a22b2c1a197c047f54b22fe7d44

This is from the background run branch so has backgroundRun in it.
Use new log events
Kill task
Make match exhaustive
Adding and killing background jobs.

The weird things it does are:
- receive an Execution start (that will start a background job)
- when receiving a JobStarted event, it flags the later execution
- when the execution ends, we artificially keep it alive
- until the job ends
New sbt-rc version and uses echo when running
Moves to sbt 0.13.6 and also latest published versions of sbt-rc and sbt-echo

Conflicts:
	ui/app/assets/plugins/run/runPluginHandler.js