Remove unneccessary requirejs config, organize modules as Require sees them

Not sure if feature detects are better in thier own top-level directory, or in
src where require assumes they will be. Trivial change either way, trying this
out for now.

Making require output a single file removes the dependency on grunt-contrib-copy
as well.

Not sure if we need findNestedDependencies. Output is same with it set to false,
so leaving out for now.
Since opts is described as config so rename the arg 'config', name exported build function

Naming the exported function gives us nicer stack traces in case of error.
Move usage comment and node requires to top of build function