fix(cache): Do not export the Cache symbol.

We did not before, don't have a good reason to export it and
it causes collisons with other packages.

Author: jbdeboer

lib/core/module.dart

@@ -23,7 +23,6 @@ export "package:angular/change_detection/change_detection.dart" show
     FieldGetterFactory;
 
 export "package:angular/cache/module.dart" show
-    Cache,
     CacheRegister,
     CacheRegisterStats;
 

test/angular_spec.dart

@@ -94,7 +94,6 @@ main() {
       var ALLOWED_NAMES = [
         "angular.app.AngularModule",
         "angular.app.Application",
-        "angular.cache.Cache",
         "angular.cache.CacheRegister",
         "angular.cache.CacheRegisterStats",
         "angular.core.annotation.ShadowRootAware",