Add CallHandler singleton and add CallView.

CallView is the container for either VideoViews or WaveformViews. All UI
elements listen for 'call_state' payloads and then call
CallHandler.getCall(roomId) to extract the current MatrixCall for that room.
We can't do this via stateful dispatches because dispatching does not preserve
ordering empirically (probably due to setTimeout).

skins/base/views/organisms/RoomView.js

@@ -26,7 +26,7 @@ var classNames = require("classnames");
 var MessageTile = ComponentBroker.get('molecules/MessageTile');
 var RoomHeader = ComponentBroker.get('molecules/RoomHeader');
 var MessageComposer = ComponentBroker.get('molecules/MessageComposer');
-var CallHandler = ComponentBroker.get("molecules/voip/CallHandler");
+var CallView = ComponentBroker.get("molecules/voip/CallView");
 
 var RoomViewController = require("../../../../src/controllers/organisms/RoomView");
 
@@ -69,7 +69,7 @@ module.exports = React.createClass({
                 <div className="mx_RoomView">
                     <RoomHeader room={this.state.room} />
                     <div className="mx_RoomView_auxPanel">
-                        <CallHandler room={this.state.room}/>
+                        <CallView room={this.state.room}/>
                     </div>
                     <div ref="messageWrapper" className="mx_RoomView_messagePanel" onScroll={this.onMessageListScroll}>
                         <div className="mx_RoomView_messageListWrapper">