better browserify supports

[wenbing]

now it can not require plugins/xxx like this

require('raven-js/plugins/console')
require('raven-js/plugins/native')

because this and global varaible Raven is used in these modules

;(function(window, Raven, console) {
}(this, Raven, console || {}));

[mattrobenolt]

I need to figure out what this even looks like since plugins are very gross at the moment.

[mattrobenolt]

Closing in favor of #282