add support for log4j.xml

[dindinw]

When the log4j.properties and log4j.xml both in classpath.
The log4j by default will load lo4j.xml instead of the log4j.properties. See :
org.apache.log4j.LogManager

       url = Loader.getResource(DEFAULT_XML_CONFIGURATION_FILE);
       if(url == null) {
         url = Loader.getResource(DEFAULT_CONFIGURATION_FILE);
       }

But if I config the loggerFactory by using foundation log in log4j.xml like:

<loggerFactory class="com.cisco.oss.foundation.logging.FoundationLogFactory"/>

The log4j load the configuration in the xml file OK, BUT:
When loggerFactory create foundation logger. It ONLY load from "log4j.properties": see com.cisco.oss.foundation.logging.FoundationLogger

              if (resource == null) {
                     resource = Loader.getResource(DEFAULT_CONFIGURATION_FILE); // NOPMD
              }

              if (resource == null) {
                     System.err.println("[FoundationLogger] Can not find resource: " + DEFAULT_CONFIGURATION_FILE); // NOPMD
                     thrownew FoundationIOException("Can not find resource: " + DEFAULT_CONFIGURATION_FILE); // NOPMD
              }

              // update the log manager to use the Foundation repository.
              final RepositorySelector foundationRepositorySelector = new FoundationRepositorySelector(FoundationLogFactory.foundationLogHierarchy);
              LogManager.setRepositorySelector(foundationRepositorySelector, null);

It will result the configuration in log4j.xml is overridden by what in the log4j.properties. For example, the level of the logger.