The files react/index.native.js and react/index.web.js ended up having
very similar source code related to initializing the Redux store. Remove
the duplication.

Additionally, I always wanted the App React Component to be consumed
without the need to provide a Redux store to it.

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

A bug was discovered in d17cc9fa which would raise a failure to push
into the browser's history if a base href was defined. Fix the failure
by removing react-router. Anyway, the usage of react-router was
incorrect because the app must hit the server infrastructure when it
enters a room because the server will choose the very app version then.

React Native provides Platform.

As a step toward merging jitsi-meet-react with jitsi-meet to share as
much source code as possible between mobile and Web, merge the part of
jitsi-meet-react's source tree which supports mobile inside the
jitsi-meet source tree and leave jitsi-meet-react's Web support in the
source code revision history but don't have it in master anymore because
it's different from jitsi-meet's Web support. In other words, the two
projects are mechanically merged at the file level and don't really
share source code between mobile and Web.

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.