Add button to stop server to QuickStart success UI

[barbeau]

Summary:

After starting the TransiTime server via Quickstart, you can't easily stop the server. It would be nice to have a button on the Quickstart success screen that would allow you to tear down the server:

Steps to reproduce:

Load any GTFS and GTFS-rt data

Expected behavior:

Allow me to stop the server from the same UI.

Observed behavior:

No obvious way to stop the server (other than killing the process manually)

[Egan109]

I've added a "Stop transiTime" button to this screen along with also being able to use the cancel button on the first/input screen during setup to stop transiTime. previously it was frozen.

eadfa42 -added stop button + gui no longer freeze's