Issue 1756 - options.IfMatch.ApplyTo and options.IfNoneMatch.ApplyTo should
return IQueryable<T> instead of IQueryable.
https://aspnetwebstack.codeplex.com/workitem/1756

Added a generic overload on Etag<T> (The type of the IfMatch and IfNoneMatch
properties on ODataQueryOptions<T>).