Fix build with Java 8 (maven-apt-plugin)

The maven-apt-plugin of org.apache.myfaces.tobago is failing when building it under java 8.

This plugin is used for org.nuxeo.ecm.platform:nuxeo-apidoc-core.

The plugin management in Nuxeo parent pom declares:

<plugin>
   <groupId>org.apache.myfaces.tobago</groupId>
   <artifactId>maven-apt-plugin</artifactId>
   <version>1.0.40</version>
   <configuration>
      <generated>/target/generated/</generated>
      <nocompile>true</nocompile>
      <target>1.6</target>
   </configuration>
</plugin>

The version should be also 1.0.41 (as existing in Nuxeo nexus repository) and java version may be forced to 1.7 for this plugin.