Make GacAssemblyLocator more robust and avoid ugly try-catch-swallow exception blocks

[taoneill]

Don't forget to send those changes downstream to Dynamite-2010 when you get a chance.

[taoneill]

Refer to: https://code.google.com/p/autofac/wiki/Scanning

And: http://msdn.microsoft.com/en-us/library/system.web.compilation.buildmanager.getreferencedassemblies(v=vs.110).aspx

... to figure out a way to make sure we don't register modules that lie outside you AppDomain's boundaries.