* feat(invite): be able to call numbers from the invite dialog

The major changes:
- Remove DialOutDialog, its views, redux hooks, css, and images.
  Its main functionality has been moved into AddPeopleDialog.
- Modify the AppPeopleDialog styling a bit so it is wider.
- Add phone numbers to AddPeopleDialog search results. Phone
  numbers are validated in parallel with the request for people
  and then appended to the result. The validation includes
  an ajax to validate the number is recognized as dialable by
  the server. The trigger for the validation is essentially if
  the entered input is numbers only.
- AddPeopleDialog holds onto the full object representation of
  an item selected in MultiSelectAutocomplete. This is so
  selected items can be removed on successful invite, leaving
  only unsuccessful items.
- More granular error handling on invite so individual invitees
  can be removed from the selected items list.

* squash: change load state, new regex for numbers

* squash: change strings, auto prepend 1 if no country code, add reminders

* Adds initial documentation for sipgw jibri.

Also explains enabling the people search service and the request/response that are made around sipgw jibri service.

* Fixes add people dialog to invite users and rooms.

No invitation is sent when there is nobody to invite.

* Reuse some recording strings, by using arguments.

* Make sure web also dispatches CONFERENCE_WILL_JOIN.

* Introduces new feature videosipgw.

* Fixes lint errors.

* Renames methods to use people, chatRooms and videoRooms.

* Updates to latest lib-jitsi-meet (dc3397b18b).

ESLint 4.8.0 discovers a lot of error related to formatting. While I
tried to fix as many of them as possible, a portion of them actually go
against our coding style. In such a case, I've disabled the indent rule
which effectively leaves it as it was before ESLint 4.8.0.

Additionally, remove jshint because it's becoming a nuisance with its
lack of understanding of ES2015+.

Prepare for React 16.

* feat(AddPeopleDialog): invite rooms

Distinguish between 'user' and 'videosipgw' search result items and
invite them with using different method.

* squash: fix typo in AddPeopleDialog.web.js

* Fix(AddPeopleDialog): Fixes error state and close dialog

* (to-squash) Addresses comments