Adjusted the result type of ajax requests

The generic result type of ajax requests were incorrect.  Now adjusted
with right values.
Renamed RxJQueryResult to RxJQueryAjaxResult
Corrected Rx.IObservable => Rx.Observable

The interface name changed in the RxJs definitions.  Corrections
reported here.
Fixed unit test too
Merge pull request #1723 from carldebilly/master

Adjusted Rx-JQuery and Rx-Knockout signatures