Update reducer.js (#2088)

_oracle service has graduated; so switching the name of the endpoint (todo: move this to the api_targets; we should keep the targets in one place)

src/js/react/Recommender/reducer.js

@@ -65,7 +65,7 @@ define(['redux', './actions'], function(
     return state;
   };
 
-  const oracleTargetState = '_oracle/readhist';
+  const oracleTargetState = 'oracle/readhist';
   const oracleTarget = (state = oracleTargetState, action) => {
     if (action.type === SET_ORACLE_TARGET && action.payload) {
       return action.payload;