[CalendarDemo] fix for aapt2 (which is now default) (#306)

When building this project with `<AndroidUseAapt>True</AndroidUseAapt2>`
you will get:

  error APT2260: obj\Debug\44\res\layout\calendarlist.xml:1: error: resource android:id/android:list not found. "android:list not found."
  error APT2260: obj\Debug\44\res\layout\eventlist.xml:1: error: resource android:id/android:list not found. "android:list not found."

I think the name `android:id/android:list` is probably just a typo, so
removing `android:` fixes the issue.

Author: jonathanpeppers

CalendarDemo/Resources/layout/CalendarList.axml

@@ -4,7 +4,7 @@
     android:layout_width="fill_parent"
     android:layout_height="fill_parent">
     <ListView
-        android:id="@android:id/android:list"
+        android:id="@android:id/list"
         android:layout_width="fill_parent"
         android:layout_height="wrap_content" />         
 </LinearLayout>

CalendarDemo/Resources/layout/EventList.axml

@@ -4,7 +4,7 @@
     android:layout_width="fill_parent"
     android:layout_height="fill_parent">
     <ListView
-        android:id="@android:id/android:list"
+        android:id="@android:id/list"
         android:layout_width="fill_parent"
         android:layout_height="wrap_content" />
     <Button