Use Maven to build OpenDJ server


Trying to bring opendj server the most possible under maven.
Here maven-antrun-plugin is only used to generate the java files from our resources.
I am sure there are many glitches that need to be fixed in this file. We'll fix them over time. It is not ready to be used as prime build system yet. For example, no tests are run yet, or several resources are missing (.properties files, other??).
My goal is to bring opendj server under Sonar in order to see code coverage data.
Use "mvn -f pom-maven.xml clean install" to compile.

build.xml:
Renamed compileadmin target to generateadmin.mvn -f pom-maven.xml clean install
Added generatesources target depending on dynamicconstants, generatemessages and generateadmin.
In generateadmin target, pass down admin.src.dir property to generateadminsubtask.

pom-maven.xml: ADDED
Inspired from pom.xml.