* 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).

The error raised by JitsiMeetJS.init() is already in the state of
features/base/lib-jitsi-meet so it's not a good design to store the same
error in the state of features/unsupported-browser.

React Native provides a Platform abstraction which React does not
provide.

As an intermediate step on the path to merging jitsi-meet and
jitsi-meet-react, import the whole source code of jitsi-meet-react as it
stands at
2f23d98424
i.e. the lastest master at the time of this import. No modifications are
applied to the imported source code in order to preserve a complete
snapshot of it in the repository of jitsi-meet and, thus, facilitate
comparison later on. Consequently, the source code of jitsi-meet and/or
jitsi-meet-react may not work. For example, jitsi-meet's jshint may be
unable to parse jitsi-meet-react's source code.