MODE-2201 Corrected the handling of non-file based URLs when reading configurations

The ability to handle non-file-based URLs was removed with a recent [commit](https://github.com/ModeShape/modeshape/commit/e8c2b5280b33408f233f2823c1740ebc6959e6ac#diff-50). This capability was added back in, and an additional test was added to read the configuration from a JAR file.