fix(undefined options passed to .get): set default options valu…

…e to `{}` (#115)

This fixes stream calls without an `options` argument.  E.g.,:

```
// This used to TypeError.
// Now it returns a stream.
const stream = core.ns.po.get();
```

#37 (comment)

lib/base.js

@@ -105,6 +105,8 @@ class BaseObject extends CallableObject {
       options = {};
     } else if (typeof options === 'string') {
       options = { name: options };
+    } else if (typeof options === 'undefined') {
+      options = {};
     }
     const qs = Object.assign({}, this.qs, options.qs || {});