Include EXEs and restrict composition pattern

FYI;

In the process of making [ScriptCs pack for SimpleWeb](https://github.com/ianbattersby/scriptcs-simpleweb) I made the following changes:

* Included EXEs as valid assembly references; probably an edge-case scenario but one I hit using Flux (Mark's little OWIN server) which is currently just a console app.

* Updated Autofac MEF Integration to 3.0.1 to resolve issue outlined in #182, I also updated AutoFac to 3.0.2 at the same time.