Bugfix: background thread object updates

Here's a new PR off of develop.   It adds the refreshing after merge fix.  
Can you give any concrete examples of said unintended side effects? I'm having trouble thinking of any. From my research last night, it seems like `refreshObject:mergeChanges:` is intended for this exact scenario, and I can't imagine why you'd ever *not* want main context objects to be updated when the same objects are updated in the background.