Improve error reportability

[jannis-baum]

• [x] make sure Vivify can output its version even when everything else fails and that it always completes the startup
  • handleArgs can be called before calling health & starting the server by instead of opening just returning a function that opens and will be called after server is running
  • completion of startup can be handled in app.ts
• [x] update bug issue template, include:
  • version
  • system info
  • vivify-server output by calling absolute path
  • custom config