[skip ci] Add missing c# tests and tweak JSON egs

This introduces test failures for c# that still need to be resolved.
Improve C# IEnumerable implementation
Update IEnumerable return type for JObject values

Return a KeyValuePair<string,dynamic> so the key isn't lost.
Update changelog
Merge pull request #60 from ResourceDataInc/dot-net-ienumerable

Improve C# IEnumerable implementation