feat(exception_handler): changed ExceptionHandler to use console.error instead of console.log

Closes #3812

modules/angular2/test/core/application_spec.ts

@@ -69,6 +69,7 @@ class HelloRootDirectiveIsNotCmp {
 class _ArrayLogger {
   res: any[] = [];
   log(s: any): void { this.res.push(s); }
+  logError(s: any): void { this.res.push(s); }
   logGroup(s: any): void { this.res.push(s); }
   logGroupEnd(){};
 }

modules/angular2/test/router/route_config_spec.ts

@@ -33,6 +33,7 @@ import {MockLocationStrategy} from 'angular2/src/mock/mock_location_strategy';
 class _ArrayLogger {
   res: any[] = [];
   log(s: any): void { this.res.push(s); }
+  logError(s: any): void { this.res.push(s); }
   logGroup(s: any): void { this.res.push(s); }
   logGroupEnd(){};
 }