Merge remote-tracking branch 'remotes/upstream/video_thumbnail' into beta

diff --cc src/com/owncloud/android/datamodel/ThumbnailsCacheManager.java
index b9087bc,68910a2..c8a06ca
--- 1/src/com/owncloud/android/datamodel/ThumbnailsCacheManager.java
--- 2/src/com/owncloud/android/datamodel/ThumbnailsCacheManager.java
+++ b/src/com/owncloud/android/datamodel/ThumbnailsCacheManager.java
@@@ -233,13 -178,11 +233,13 @@@ public class ThumbnailsCacheManager 
                  }
  
                  mFile = params[0];
 +                mIsThumbnail = (Boolean) params[1];
 +
                  
                  if (mFile instanceof OCFile) {
 -                    thumbnail = doOCFileInBackground();
 +                    thumbnail = doOCFileInBackground(mIsThumbnail);
  
-                     if (((OCFile) mFile).isVideo()){
+                     if (((OCFile) mFile).isVideo() && thumbnail != null){
                          thumbnail = addVideoOverlay(thumbnail);
                      }
                  }  else if (mFile instanceof File) {