build(npm): add es6-promise as a dependency

This is actually an inherited dependency that comes from zone.js.

See related issue: https://github.com/angular/zone.js/issues/212

It would be better to make this one an optionalPeerDependency but npm
currently doesn't support making peerDependencies optional.
See: https://github.com/npm/npm/issues/3066

npm-shrinkwrap.clean.json

@@ -3619,6 +3619,9 @@
         }
       }
     },
+    "es6-promise": {
+      "version": "3.0.2"
+    },
     "es6-shim": {
       "version": "0.33.10"
     },

npm-shrinkwrap.json

@@ -5548,6 +5548,11 @@
         }
       }
     },
+    "es6-promise": {
+      "version": "3.0.2",
+      "from": "es6-promise@*",
+      "resolved": "https://registry.npmjs.org/es6-promise/-/es6-promise-3.0.2.tgz"
+    },
     "es6-shim": {
       "version": "0.33.10",
       "from": "https://registry.npmjs.org/es6-shim/-/es6-shim-0.33.10.tgz",

package.json

@@ -31,6 +31,7 @@
     "test": "gulp test.all.js && gulp test.all.dart"
   },
   "dependencies": {
+    "es6-promise": "^3.0.2",
     "es6-shim": "^0.33.3",
     "reflect-metadata": "0.1.2",
     "rxjs": "5.0.0-alpha.13",