Change order of config file locations to be more natural

The most natural order is "more specific locations win". That way
if a use has application.properties in the root of a JAR (as is
normal), overrides can always be made on
classpath:/config/application.properties (as well as
file:./application.properties which has always been the case).

Before this change properties in classpath:/config/* were over
written by those in the root location, not the other way round.

Fixes gh-527