Strauss doesn't handle file autoloading rules

[TimothyBJacobs]

An issue we ran into when deploying Strauss for iThemes Security is that the generated Strauss autoloader does not handle composer packages that contain a files autoload directive. For instance, beberlei/assert.

We were able to use the suggested fix. However, this also requires enabling Authoritative Classmaps in Composer to fix generating an invalid autoloader.