soft exit when stdin ends

to avoid having to use `taskkill` (which prevents cleanup of `.tern-port`) on windows:
- listen to `stdin` and soft exit on `end`
- bump package version so editor plugins can refer to this

NOTES:
- matching pull request for tern_for_vim, "rely on tern soft exiting when its stdin ends"
- you'll want to check when other editor plugins close tern's stdin