Update util imports to play nicely with UMD

Author: bitpshr

src/index.ts

@@ -1,5 +1,3 @@
-import * as util from './util';
-
 export * from './AccountTrackerController';
 export * from './AddressBookController';
 export * from './BaseController';
@@ -13,4 +11,4 @@ export * from './PhishingController';
 export * from './PreferencesController';
 export * from './ShapeShiftController';
 export * from './TokenRatesController';
-export { util };
+export * from './util';

src/util.ts

@@ -67,3 +67,9 @@ export async function safelyExecute(operation: () => Promise<any>) {
 		/* tslint:disable-next-line:no-empty */
 	}
 }
+
+export default {
+	getBuyURL,
+	getGasPrice,
+	safelyExecute
+};