chore(types): specify @types/node version (#136)

this commit add @types/node to the dependencies manifest for the router.
when trying to build this package without an earlier version of these
types, compilation fails. the compilation fails due to @types/node being
hoisted from the np package, and the types being hoisted are
incompatible with the version of typescript that is used with v1 of
stencil

packages/router/package.json

@@ -27,6 +27,7 @@
     "@stencil/state-tunnel": "^1.0.1"
   },
   "devDependencies": {
+    "@types/node": "12.0.0",
     "np": "^5.0.3"
   },
   "author": "Ionic Team",