Exposed the RKObjectRequestOperation in RKPaginator so that the developer has access to the request objects provided by the operation upon completion.
Set RKPaginator's objectRequestOperation to readonly as there is no need to set the operation for the class.
Fixed an issue where objectRequestOperations would get invalidated upon every call of loadPage even if there is a previous operation in progress. I've updated this to determine whether we've received a response from the operation instead.
Added test to determine whether an assertion is thrown while load is called while another is still processing.
Added test to determine if the objectRequestOperation is populated after loading.
Added test to determine if the objectRequestOperation from one load: is different after the next load: method is called.