Merge pull request #24 from spacepluk/fix-uncaught-exception

fix uncaught exception
Merge pull request #25 from spacepluk/downgradw-brfs

downgrade brfs to `1.0.2`
2.3.1
allow strings in opts.require and opts.external
rename files to file to be consistent with browserify
FIX opts 'retainName' from atomify gets passed on. Fixes atomify#44
Merge pull request #27 from serapath/github.com/atomify/atomify/issues/44

FIX opts 'retainName' from atomify gets passed on. Fixes atomify#44
Merge pull request #23 from spacepluk/master

expose browserify's `require` and `external` methods