Maven via Github-Maven-Registry instead of OSS-Nexus

[kfriedberger]

There are several Maven providers. Currently the first pushed provider is OSS-Nexus, that was integrated long time back.

It lacks documentation for new users/admins and is not really nice to use. It works well.

We might think about using Github Maven Registry, such that there is no external service/account needed.

[kfriedberger]

The existing Ant-Maven plugin uses deprecated features of the JVM, aka SecuityManager:

artifact:mvn] Java Result: -1
[artifact:mvn] java.lang.UnsupportedOperationException: The Security Manager is deprecated and will be removed in a future release
[artifact:mvn] 	at org.apache.tools.ant.taskdefs.ExecuteJava.execute(ExecuteJava.java:194)
[artifact:mvn] 	at org.apache.tools.ant.taskdefs.Java.run(Java.java:891)
[artifact:mvn] 	at org.apache.tools.ant.taskdefs.Java.executeJava(Java.java:231)
[artifact:mvn] 	at org.apache.tools.ant.taskdefs.Java.executeJava(Java.java:135)
...

Currently, we still can avoid the error by using ANT_OPTS="-Djava.security.manager=allow" as environemnt variable.