Datagraph 352/330

@jexp - initial attempt to fix sorting and paging however there is no 100% clear and neat fix at present as far as I can see. This will work for the majority of cases (where sort property is referring to an actual property) however for cases where people are using "other" things (such as a function) instead of a property, it won't work (see my ignored test GraphRepositoryTests.findAllSortedWithFunction() for an example here).

Keen to hear your thoughts, and whether we need to worry about these "other" cases, or indeed if there are additional things I have not considered. We could make it a bit more clever to deal with these cases as well if need be (dynamically determine if its really a property and deal accordingly) however that would add additional overhead. 

Thanks
Nicki