fix(ts-errors): Resolve small typescript errors

Type 'String' is not assignable to type 'string'.
  'string' is a primitive, but 'String' is a wrapper object. Prefer using 'string' when possible.

Author: hypery2k

urlhandler.d.ts

@@ -1,6 +1,6 @@
 export interface UrlHandlerCallback { (data: any): void; }
 export interface AppURL {
-    path: String;
-    params: Map<String, String>;
+    path: string;
+    params: Map<string, string>;
 }
 export function handleOpenURL(handler: UrlHandlerCallback): void;