Polish
Find 'messages*.properties' in all jar URLs

Update the the PathMatchingResourcePatternResolver used in the
MessageSourceAutoConfiguration condition to deal with the fact
that `classpath*:` patterns do not work with URLClassLoaders when
the pattern doesn't include a folder.

The ExtendedPathMatchingResourcePatternResolver works by searching
all classpath URLs when the `findAllClassPathResources` method is
called with an empty location.

Fixes gh-1378