add actions in the preview

src/com/owncloud/android/ui/preview/PreviewImageFragment.java

@@ -306,7 +306,14 @@ public class PreviewImageFragment extends FileFragment {
                 mContainerActivity.getFileOperationsHelper().syncFile(getFile());
                 return true;
             }
-            
+            case R.id.action_favorite_file:{
+                mContainerActivity.getFileOperationsHelper().toggleKeepInSync(getFile(), true);
+                return true;
+            }
+            case R.id.action_unfavorite_file:{
+                mContainerActivity.getFileOperationsHelper().toggleKeepInSync(getFile(), false);
+                return true;
+            }
             default:
                 return false;
         }

src/com/owncloud/android/ui/preview/PreviewMediaFragment.java

@@ -341,7 +341,14 @@ public class PreviewMediaFragment extends FileFragment implements
                 mContainerActivity.getFileOperationsHelper().syncFile(getFile());
                 return true;
             }
-
+            case R.id.action_favorite_file:{
+                mContainerActivity.getFileOperationsHelper().toggleKeepInSync(getFile(), true);
+                return true;
+            }
+            case R.id.action_unfavorite_file:{
+                mContainerActivity.getFileOperationsHelper().toggleKeepInSync(getFile(), false);
+                return true;
+            }
             default:
                 return false;
         }