* fix(connection): reload immediately on possible split-brain

There isn't an explicit way to know when a split brain
scenario has happened. It is assumed it arises when an
"item-not-found" connection error is encountered early
on in the conference. So, store when a connection has
happened so it be calculated how much time has
elapsed and if the threshold has not been exceeded
then do an immediate reload of the app instead of
showing the overlay with a reload timer.

* squash: rename isItemNotFoundError -> isShardChangedError

Currently the listeners for disconnected and failed connection events
are unsubscribed as soon as the connection is established, so
the CONNECTION_DISCONNECTED is never triggered which would clear the
'connection' field. This commit will clear the 'connection' state on
CONNECTION_WILL_CONNECT. It's needed anyway given that there's no
guarantee on when and if the async disconnect operation will finish.

One issue caused by the 'connection' not cleared was that
CONNECTION_FAILED was not reduced correctly and the reload screen was
not displayed for the following scenario:
1. Join and leave any working conference.
2. Turn off network connectivity on the device.
3. Wait for CONNECTION_FAILED. The reload screen will not be displayed,
   because CONNECTION_FAILED is not reduced correctly, because the old
   'connection' value is still there.

Introduce ConnectionFailedError type.

Delay the CONFERENCE_FAILED event until the user cancels the login
dialog using the 'recoverable' event flag.

Properly handle errors while connecting or joining a conference. Prior to this
patch, only errors on established conferences / connections were saved to the
redux store.

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+.

Gradually, we exploded the error of CONNECTION_FAILED in multiple
redux state properties. The explosion makes maintenance harder because
the properties have to be updated in sync. Collect them in an object
resembling an Error instance.

Do not show the 'Password is incorrect' message when the LoginDialog
opens for the first time.

In order to support XMPP authentication, we'll need the message
accompanying the error and carried by lib-jitsi-meet's
CONFERENCE_FAILED in the redux store. We already carry the message in
the redux action and we've got the error in the redux store.

Keep track of the connection and conference objects so we can leave and / or
disconnect early, before the connection is established or the conference joined.

There were getDomain, setDomain, SET_DOMAIN, setRoomURL, SET_ROOM_URL
which together were repeating one and the same information and in the
case of the 'room URL' abstraction was not 100% accurate because it
would exist even when there was no room. Replace them all with a
'location URL' abstraction which exists with or without a room.

Then the 'room URL' abstraction was not used in (mobile) feature
share-room. Use the 'location URL' there now.

Finally, removes source code duplication in supporting the Web
application context root.

Rename setStateProperties and setStateProperty to assign and set,
respectively. Inspired by Object.assign, _.assign, and _.set.

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.