in the AMD case, reveal the global right away

This is to accomodate synchronous code that might be running alongside AMD modules.  The AMD case already exposes the `window.Raven` global, however previous to this patch it waited until the AMD module was specified as a dependency before initializing the global.

I figure that if the global is going to be exposed in the AMD case, it
may as well happen right away, so non-AMD code can depend on it being
there. :)