Fix browserify options

`insertGlobals` is a bundle option and should be passed in the `bundle` method.
Now it is passed to the browserify constructor and it has no effect.
That option has a boolean value according to [browserify documentation](https://github.com/substack/node-browserify#bbundleopts-cb) and is `false` by default.

I think that `detectGlobals` (enabled by default) does what `insertGlobals` was meant to do here.