Added SectionedViewDataSourceType conformance to table/collection vie…

[Granfalloner]

…w data sources. It eliminates the need to manually reimplement functionality already present in RxCocoa (like modelSelected, modelDeselected, etc).

[icanzilb]

I'll have a look! Since the class supports SectionedViewDataSourceType how is the section support implemented?

[Granfalloner]

I think naming of protocol SectionedViewDataSourceType is somewhat misleading. It does not require you to implement sectioned data source - it's rather general protocol that requires you to make sure your data source can provide item at given index path (which includes section as well). For example, RxCocoa implementation of non-sectioned RxTableViewReactiveArrayDataSource also conforms to this protocol, although it does not support sections.