remove asynchronous execution of deferred dependent observables

this is in regards to https://github.com/SteveSanderson/knockout.mapping/issues/95

I'm not certain why the deffered DO's must be evaluated asynchronously, they should be determined prior to outermost fromJS returning right?  I can assume they must happen after, but none of the unit tests seem to make that necessary.  

I tweaked some unit tests per evaluation at https://github.com/SteveSanderson/knockout.mapping/issues/95#issuecomment-12022149  if you don't agree with those tweaks then this pull wont' make sense.  would love to know the reason behind the async and make a test that enforces that intent instead of some that just verify the behaviour.