Re-introduced the possibility to set disable autoShow for banner views.

Probably by accident, the check for autoShow had been removed by
@floatinghotpot on July 31, 2016 [1]. This lead to a short flickering
(up to some seconds depending on the speed of the device and the
Internet connection) for empty ad codes (e.g., due to frequency capping)
before the library recognized that the ad code was currently unfilled.

The behaviour of the plugin should now again be as before:
- By default, the Java code sets autoShow to true
- Setting autoShow explicitly to false in JavaScript should be reflected
again now


[1]
https://github.com/aimpulse/cordova-plugin-admob/commit/f38a9cf559b1941255e75d68b33543223e748922#diff-89df21a171ffd69d7750e57d0490022f

src/android/AdMob.java

@@ -227,9 +227,9 @@ public void run() {
                 bannerVisible = false;
                 adView.loadAd( buildAdRequest() );
 
-                //if(autoShowBanner) {
+                if(autoShowBanner) {
                     executeShowAd(true, null);
-                //}
+                }
                 Log.w("banner", publisherId);
 
                 if(delayCallback!=null)