Errors in feature config files are not reported enough

Some XML configuration files packaged in features encourage users to make manual edits. But if a user makes a typo, it is not reported back, configuration file is ignored instead. More precisely, the user gets a message ending with something like
etc/opendaylight/karaf/41-bgp-example.xml is not a config subsystem config file
on level DEBUG and that is it. As default log level is INFO, currently the user is left wondering about what went wrong. Pre-karaf ODL builds used to print out full exception, which was helpful in localizing error in config file. This can be considered a bug, as existing functionality is not exercised just because configuration file comes from a feature.