remove trailing white spaces
act cannot be private, because we need to use it in a subclass
Merge pull request #1 from phunehehe/fix-compilation-error

Fix compilation error
synchronize when getting Bitmap from cache, because maybe the cache will be assigned to null by method clearCache
synchronize cache in method clearCache
Merge pull request #2 from nguyenhuy/NPE_in_BitmapAjaxCallback.memGet

synchronize when getting Bitmap from cache, because maybe the cache will...