* feat(display-name): convert to React

- Create a new React Component for displaying and updating display
  names on small videos
- The updating of the Component is defined in the parent class
  SmallVideo, which children will get access to through prototype
  copying
- Create a new actionType and middleware so name changes that occur
  in DisplayName can be propogated to outside redux
- Update the local video's DisplayName when a conference is joined
  or else the component may keep an undefined user id

* squash: query for the container, not the el owned by react

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.