[DOXIA-610] Drop dependency to outdated Log4j

Use default configuration - jdk logger
diff --git a/doxia-modules/doxia-module-fo/pom.xml b/doxia-modules/doxia-module-fo/pom.xml
index a8ecdf7..35e1fb4 100644
--- a/doxia-modules/doxia-module-fo/pom.xml
+++ b/doxia-modules/doxia-module-fo/pom.xml
@@ -99,13 +99,6 @@
       </exclusions>
     </dependency>
     <dependency>
-      <groupId>log4j</groupId>
-      <artifactId>log4j</artifactId>
-      <version>1.2.17</version>
-      <!-- runtime dep for fop -->
-      <scope>runtime</scope>
-    </dependency>
-    <dependency>
       <groupId>org.xmlunit</groupId>
       <artifactId>xmlunit-core</artifactId>
       <scope>test</scope>
diff --git a/doxia-modules/doxia-module-fo/src/main/resources/log4j.properties b/doxia-modules/doxia-module-fo/src/main/resources/log4j.properties
deleted file mode 100644
index 96a29e0..0000000
--- a/doxia-modules/doxia-module-fo/src/main/resources/log4j.properties
+++ /dev/null
@@ -1,24 +0,0 @@
-# Licensed to the Apache Software Foundation (ASF) under one
-# or more contributor license agreements.  See the NOTICE file
-# distributed with this work for additional information
-# regarding copyright ownership.  The ASF licenses this file
-# to you under the Apache License, Version 2.0 (the
-# "License"); you may not use this file except in compliance
-# with the License.  You may obtain a copy of the License at
-#
-#   http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing,
-# software distributed under the License is distributed on an
-# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-# KIND, either express or implied.  See the License for the
-# specific language governing permissions and limitations
-# under the License.
-
-log4j.rootCategory=INFO, stdout
-
-log4j.appender.stdout=org.apache.log4j.ConsoleAppender
-log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
-log4j.appender.stdout.layout.ConversionPattern=%5p [%c:%L] %d{ISO8601} - %m%n
-
-log4j.logger.org.apache.fop=ERROR