Pass the java handle down to the base constructor to avoid a potentia…

…lly nasty leak

I haven't seen this in the wild but it should prevent a disconnect between the java and c#
if instantiating the activity from java. I don't *think* we'd hit this unless starting an activity
from an intent on the java side of things and we happened to override a virtual method called
from one of the constructors.

See http://developer.xamarin.com/guides/android/under_the_hood/architecture/#Java_Activation

Cirrious/Cirrious.MvvmCross.Droid/Views/MvxActivity.cs

@@ -22,6 +22,7 @@ public abstract class MvxActivity
     {
 
         protected MvxActivity(IntPtr javaReference, JniHandleOwnership transfer)
+            : base(javaReference, transfer)
         {
             BindingContext = new MvxAndroidBindingContext(this, this);
             this.AddEventListeners();

CrossCore/Cirrious.CrossCore.Droid/Views/MvxEventSourceActivity.cs

@@ -24,7 +24,8 @@ protected MvxEventSourceActivity()
 
         }
 
-        protected MvxEventSourceActivity(IntPtr javaReference, JniHandleOwnership transfer) { }
+        protected MvxEventSourceActivity(IntPtr javaReference, JniHandleOwnership transfer)
+            : base(javaReference, transfer) { }
 
         protected override void OnCreate(Bundle bundle)
         {