Deprecate aggregate in favor of reduce

We have had aggregate from Rx.Net for a while but long ago migrated to reduce as the primary. Time to deprecate it.

Author: benjchristensen

rxjava-core/src/main/java/rx/Observable.java

@@ -5139,6 +5139,7 @@ public ConnectableObservable<T> publishLast() {
      *
      * @see <a href="https://github.com/Netflix/RxJava/wiki/Transforming-Observables#reduce-or-aggregate">RxJava Wiki: aggregate()</a>
      * @see #reduce(Func2)
+     * @deprecated
      */
     public Observable<T> aggregate(Func2<T, T, T> accumulator) {
         return reduce(accumulator);
@@ -5181,6 +5182,7 @@ public <R> Observable<R> reduce(R initialValue, Func2<R, ? super T, R> accumulat
      * 
      * @see <a href="https://github.com/Netflix/RxJava/wiki/Transforming-Observables#reduce-or-aggregate">RxJava Wiki: aggregate()</a>
      * @see #reduce(Object, Func2)
+     * @deprecated
      */
     public <R> Observable<R> aggregate(R initialValue, Func2<R, ? super T, R> accumulator) {
         return reduce(initialValue, accumulator);