Builds are now themselves UMD modules, so they could be `require`'d like any
other AMD module or they can still be used as old ES5 modules with globals.

Additionally the build is now closured, so that the almond API doesn't pollute
the global context with `define` or `require`. This does however mean that
`require` can no longer be used outside of the build (unless requirej.s is
included directly.