Adds a check for taskkey in integration test

It only checks for the initial value, not if events are sent when the value changes
later on.
Fix issue where command engine was using stale server state.

* Force command engine to read serverState *after* grabing the latest command to execute.
* Remove completed TODOs
* Complete @skyluc's test for watching tasks.
Fix integration test for other platforms.
Merge pull request #73 from sbt/issue/taskkey-value-test

TaskKey events fired immediately now.