Assorted improvements

[dfreeman]

Took a little time after lunch to clean up some things I noticed this morning:

• our Serve subclass now calls the superclass's onInterrupt so the build shuts down cleanly on ctrl-c
• the temporary output directory moved to the system tempdir (watching/rebuilds still work just fine locally) to avoid needing to configure exclusions for .e-c-ts in the project dir
• there should be no more thrashing rebuilds between the tsc watcher and the ember-cli watcher:
  • ember serve-ts now waits for the initial compilation to complete before building the rest of the app, so the compiled JS is already present in the output directory when the first build runs
  • switching from exclude to include in the default tsconfig.json gets tsc to ignore the contents of tmp (though this does make things a little more interesting with addons/module unification down the line)
• the emitted app URL (Serving on http://localhost:4200/) should be correct now

[chriskrycho]

EXCELLENT.