This pull request contains fix to MMRecord batch request issue

Problem : "startBatchedRequest.." method is failing to call completionBlock(), when one/all of the API call gets failed. 
Solution: I gone through the MMRecord batch request code and found that MMRecord is not calling "dispatch_group_leave(state.dispatchGroup);" in faillure block. In this pull request I have added code which informs the DispatchGroup that task has been completed by calling "dispatch_group_leave", this way completionBlock() is getting called when all of its batch request completes their execution regardless of their results.