Updates CoreAudio to be default and echo cancel to be activated for it by default on macosx.

src/org/jitsi/impl/neomedia/device/DeviceSystem.java

@@ -194,8 +194,8 @@ public static void initializeDeviceSystems(MediaType mediaType)
                         ? ".PulseAudioSystem"
                         : null,
                     OSUtils.IS_WINDOWS ? ".WASAPISystem" : null,
-                    OSUtils.IS_ANDROID ? null : ".PortAudioSystem",
                     OSUtils.IS_MAC ? ".MacCoreaudioSystem" : null,
+                    OSUtils.IS_ANDROID ? null : ".PortAudioSystem",
                     ".NoneAudioSystem"
                 };
             break;

src/org/jitsi/impl/neomedia/device/MacCoreaudioSystem.java

@@ -805,7 +805,7 @@ public String toString()
      */
     public static boolean isEchoCancelActivated()
     {
-        boolean isEchoCancel = false;
+        boolean isEchoCancel = true;
 
         ConfigurationService cfg = LibJitsi.getConfigurationService();
         if (cfg != null)