build: added imports of rxjs utility functions

public/app/features/plugins/plugin_loader.ts

@@ -9,8 +9,6 @@ import config from 'app/core/config';
 import TimeSeries from 'app/core/time_series2';
 import TableModel from 'app/core/table_model';
 import {coreModule, appEvents, contextSrv} from 'app/core/core';
-import {Observable} from 'rxjs/Observable';
-import {Subject} from 'rxjs/Subject';
 import * as datemath from 'app/core/utils/datemath';
 import * as fileExport from 'app/core/utils/file_export';
 import * as flatten from 'app/core/utils/flatten';
@@ -18,6 +16,16 @@ import * as ticks from 'app/core/utils/ticks';
 import builtInPlugins from './buit_in_plugins';
 import d3 from 'vendor/d3/d3';
 
+// rxjs
+import {Observable} from 'rxjs/Observable';
+import {Subject} from 'rxjs/Subject';
+
+// these imports add functions to Observable
+import 'rxjs/add/observable/empty';
+import 'rxjs/add/observable/from';
+import 'rxjs/add/operator/map';
+import 'rxjs/add/operator/combineAll';
+
 System.config({
   baseURL: 'public',
   defaultExtension: 'js',
@@ -57,7 +65,6 @@ exposeToPlugin('rxjs/Observable', Observable);
 exposeToPlugin('d3', d3);
 
 exposeToPlugin('app/plugins/sdk', sdk);
-
 exposeToPlugin('app/core/utils/datemath', datemath);
 exposeToPlugin('app/core/utils/file_export', fileExport);
 exposeToPlugin('app/core/utils/flatten', flatten);