Fixed chai bindings so that now they work with CommonJS; added tests

chai/chai-assert.d.ts

@@ -129,7 +129,3 @@ declare module chai {
 
 //browser global
 declare var assert:chai.Assert;
-
-declare module 'chai' {
-export = chai;
-}

chai/chai.d.ts

@@ -162,3 +162,7 @@ declare module chai {
         (constructor: Function, expected?: RegExp, message?: string): Expect;
     }
 }
+
+declare module "chai" {
+    export = chai;
+}