Introduced two flags: one for investigating and one for who is investigating.

- respective code added in db migration, controller to accept new params
  and frontend app
- right now, investigating person is set to none when environment is set
  as back up again
Lint fixes after Mario's pull request.

Closes #4
Fixed error to be an object instead of string passed on GET flags failure.
Added investigation info when opening a flag when it is both down and no one is investigating it.