Bundle ios_webkit_debug_proxy for OS X. Fixes #37.

This includes the iOS proxy into the add-on for OS X.

The process to start things like iOS from WebIDE is still crazy, but I'm actively fixing up how the WebIDE API to this add-on separately.
No, only a single fix is needed, and even then only if used via jpm. Release builds never need this fix. But, testing whether you have the permissions you need is as much work as just fixing them every time it seems... Unless you have a nicer suggestion in mind!