In cases where a module may be installed that doesn't have a config.xml
file, this will throw.  I think I hit this once when there was a module
that was installed in app/etc/modules but didn't have any actual module
directory or config.xml.
Updated composer.lock
Merge pull request #81 from sparcksoft/fix-empty-config-xml

Fix for cases where a module may be installed that doesn't have a config.xml
Fixed issue #81 Fix for cases where a module may be installed that doesn't have a config.xml