Raise warning or exception when calling Series.sort when do not own data

[wesm]

For example, when part of a DataFrame, can result in the source array being modified in place

[wesm]

This may be impossible as every ndarray subclass is a view of the original ndarray and thus does not own its own data. Punting to 0.6-- maybe Series should keep a reference to its parent DataFrame? Potentially a nightmare to maintain

[wesm]

I figured out how to do this by following the ndarray.base to the source