Fix incorrect normalize path in optimized output

Optimized output included a require(['css', 'path/to/normalize.js', ...]) call.

The .js suffix causes the RequireJS base URL to be ignored when loading the normalize module (and instead tries to load it by appending path/to/normalize.js directly to the page URL).

This change fixes the issue for me, though there may be a more appropriate place to put it :)
Merge pull request #30 from kmontag/patch-1

Fix incorrect normalize path in optimized output