Fix possible NPE.

Change-Id: Ifca1e64aacf0f4b4e83f70c9bcbe6bb79f5415fd

android/sdremote/src/org/libreoffice/impressremote/activity/SlideShowActivity.java

@@ -151,6 +151,10 @@ public class SlideShowActivity extends SherlockFragmentActivity implements Servi
     }
 
     private void startSlideShow() {
+        if (!isServiceBound()) {
+            return;
+        }
+
         if (mCommunicationService.getSlideShow().isRunning()) {
             setUpSlideShowInformation();
             return;

android/sdremote/src/org/libreoffice/impressremote/fragment/ComputersFragment.java

@@ -459,6 +459,10 @@ public class ComputersFragment extends SherlockListFragment implements ServiceCo
     }
 
     private void stopComputersSearch() {
+        if (!isServiceBound()) {
+            return;
+        }
+
         mCommunicationService.stopServersSearch();
     }
 

android/sdremote/src/org/libreoffice/impressremote/fragment/SlidesPagerFragment.java

@@ -119,6 +119,10 @@ public class SlidesPagerFragment extends SherlockFragment implements ServiceConn
     }
 
     private void setUpCurrentSlide() {
+        if (!isServiceBound()) {
+            return;
+        }
+
         SlideShow aSlideShow = mCommunicationService.getSlideShow();
 
         getSlidesPager().setCurrentItem(aSlideShow.getCurrentSlideIndex());