Fix elastic.js typings. Adding module and namespace exports. (#14152)

* Fix elastic.js typings namespace from 'elasticjs' to 'elastic.js'.

 This will allow using 'import' statement against elastic.js like so:
 import * as elasticjs from 'elastic.js';

 This also makes using this typings to be TSlint "no-var-require" rule compliant.

* Export elasticjs namespace.

elastic.js/elastic.js-tests.ts

@@ -1,3 +1,5 @@
+import * as elasticjs from 'elastic.js';
+
 let body = new elasticjs.Request({})
   .query(new elasticjs.MatchQuery('title_field', 'testQuery'))
   .facet(new elasticjs.TermsFacet('tags').field('tags'))

elastic.js/index.d.ts

@@ -3,6 +3,10 @@
 // Definitions by: Oleksii Trekhleb <https://ua.linkedin.com/in/trekhleb>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 
+export = elasticjs;
+
+export as namespace elasticjs;
+
 declare module elasticjs {
 
   export interface Facet {}