We weren't setting the location of the resource bundle correctly in the
renderer process. It turns out base::mac::OuterBundle() returns the helper
app's bundle in the renderer process. So now we have MainApplicationBundle() to
give us the bundle of the main app.
We deduce the name of the application from the CFBundleName of the .app bundle
and use a path based on that. Similar logic should be implementable for other
platforms.
Fixes#3.