migrate to "export default"

also, set no-use-before-define in linter

src/test/openssl-test.js

@@ -2,7 +2,7 @@
 
 import BoxError from '../boxerror.js';
 import expect from 'expect.js';
-import * as openssl from '../openssl.js';
+import openssl from '../openssl.js';
 import safe from 'safetydance';
 
 /* global describe:false */