Server stays running on exit, restart

[rashidkpc]

The server exit no longer seems to function correctly in dev mode. It often leaves a process hanging and continues to serve request. Also, when the auto restart works, it seems to leave another process running serving the old code.

Currently to make changes to the server code one must killall -9 iojs to ensure changes are reflected

[spalger]

To replicate this:

1. delete your optimize/bundles directory

2. create an empty file at optimize/bundles/webpack.records

3. in a console tab, run this script to repeatedly log the iojs process list

   while [ 1 ]; do ps | grep iojs; sleep 1; clear; done

4. in another console tab run the kibana server in dev mode

   ./bin/kibana --dev

5. observe the server logging optimizer crashed with status code 1 and the process list growing by one each time you do _#_4

6. Finally killall iojs