Offline mode (#1723)

* Allow the client to run without connection to HS (i.e. using indexeddb)

Allows running without having pushRules (it's safe not to have these 
when running from indexeddb sync.)

This means rooms will be displayed with "unknown" notifcation state.

This assumes anything that uses the push rules will get pushRule state
again when the client starts syncing again.

For recovering from being disconnected, 
* If an avatar has fallen back, try again on reconnection
* If a thumbnail image failed to load, retry on reconnect
* Load joined groups when reconnecting

Update tests to give MELS a context.matrixClient

src/components/views/elements/Pill.js

@@ -17,7 +17,7 @@ import React from 'react';
 import sdk from '../../../index';
 import dis from '../../../dispatcher';
 import classNames from 'classnames';
-import { Room, RoomMember } from 'matrix-js-sdk';
+import { Room, RoomMember, MatrixClient } from 'matrix-js-sdk';
 import PropTypes from 'prop-types';
 import MatrixClientPeg from '../../../MatrixClientPeg';
 import { MATRIXTO_URL_PATTERN } from '../../../linkify-matrix';
@@ -61,6 +61,17 @@ const Pill = React.createClass({
         shouldShowPillAvatar: PropTypes.bool,
     },
 
+
+    childContextTypes: {
+        matrixClient: PropTypes.instanceOf(MatrixClient),
+    },
+
+    getChildContext() {
+        return {
+            matrixClient: this._matrixClient,
+        };
+    },
+
     getInitialState() {
         return {
             // ID/alias of the room/user
@@ -135,6 +146,7 @@ const Pill = React.createClass({
 
     componentWillMount() {
         this._unmounted = false;
+        this._matrixClient = MatrixClientPeg.get();
         this.componentWillReceiveProps(this.props);
     },