fix(statistics) initialize LocalStatsCollector on Statistics.init

Creating the AudioContext at import time means a warning line is printed
in the JS console even before the user has a chance of initializing the
library, which is weird.

There is no harm in initializing it in init since it's the first thing
the user needs to do in order to use the library.

modules/statistics/LocalStatsCollector.js

@@ -136,6 +136,13 @@ LocalStatsCollector.prototype.stop = function() {
     this.source = null;
 };
 
+/**
+ * Initialize collector.
+ */
+LocalStatsCollector.init = function() {
+    LocalStatsCollector.connectAudioContext();
+};
+
 /**
  * Checks if the environment has the necessary conditions to support
  * collecting stats from local streams.
@@ -170,8 +177,3 @@ LocalStatsCollector.connectAudioContext = function() {
 
     context.suspend();
 };
-
-/**
- * Initialize the audio context on startup.
- */
-LocalStatsCollector.connectAudioContext();

modules/statistics/statistics.js

@@ -40,6 +40,8 @@ Statistics.init = function(options) {
 
     Statistics.disableThirdPartyRequests = options.disableThirdPartyRequests;
 
+    LocalStats.init();
+
     // WatchRTC is not required to work for react native
     browser.isReactNative()
         ? logger.warn('Cannot initialize WatchRTC in a react native environment!')