feat(AjaxObservable) : support 'PATCH' request type
feat(AjaxObservable) : support 'PATCH' request type

Add support of the 'PATCH' request type based on the already existing 'PUT' request.

Brocco/RxJS,Brocco/RxJS,jayphelps/rxjs,martinsik/rxjs,jayphelps/rxjs,jayphelps/rxjs,ReactiveX/rxjs,IgorMinar/RxJS,RxJS-CN/RxJS-Docs-CN,trxcllnt/RxJS,martinsik/rxjs,kwonoj/RxJS,benlesh/RxJS,kwonoj/RxJS,trxcllnt/RxJS,Brocco/RxJS,ReactiveX/rxjs,RxJS-CN/RxJS-Docs-CN,kwonoj/RxJS,Brocco/RxJS,benlesh/RxJS,IgorMinar/RxJS,benlesh/RxJS,ReactiveX/RxJS,SangKa/RxJS-Docs-CN,trxcllnt/RxJS,SangKa/RxJS-Docs-CN,ReactiveX/rxjs,RxJS-CN/RxJS-Docs-CN,ReactiveX/rxjs,trxcllnt/RxJS,jayphelps/rxjs,martinsik/rxjs,SangKa/RxJS-Docs-CN,benlesh/RxJS,ReactiveX/RxJS,ReactiveX/RxJS,martinsik/rxjs,jayphelps/rxjs,kwonoj/RxJS,ReactiveX/RxJS,SangKa/RxJS-Docs-CN,RxJS-CN/RxJS-Docs-CN