sdremote - always replace fragments, to avoid stale content

With Change-Id I7cb1cf29bcae59ef26cf3bf0c2b3dd028eb8f878, this code
gets run on every onCreate, thus adding activities on top of
existing ones. Seems FragmentManager lifetime is a bit decoupled
from Activity

Change-Id: Icc1dc86ef91257ce734ee00fed83e909ddf52dc8
Signed-off-by: Michael Meeks <michael.meeks@suse.com>

android/sdremote/src/org/libreoffice/impressremote/PresentationActivity.java

@@ -78,8 +78,8 @@ public class PresentationActivity extends SherlockFragmentActivity {
 
         FragmentTransaction fragmentTransaction = fragmentManager
             .beginTransaction();
-        fragmentTransaction.add(R.id.presentation_interceptor,
-                                mPresentationFragment, "fragment_presentation");
+        fragmentTransaction.replace(R.id.presentation_interceptor,
+                                    mPresentationFragment, "fragment_presentation");
         fragmentTransaction.commit();
         mOuterLayout = (FrameLayout) findViewById(R.id.framelayout);
     }