Update sample configuration to use agentlib:jdwp Java 5 option

Since Java 5, the option agentlib:jdwp replaces -Xdebug -Xrunjdwp:.

We should update the reference in Nuxeo sources. Especially the sample configuration in https://github.com/nuxeo/nuxeo-distribution/blob/master/nuxeo-distribution-resources/src/main/resources/bin/nuxeo.conf

See http://docs.oracle.com/javase/7/docs/technotes/guides/jpda/conninv.html

Basically,
-Xdebug -Xrunjdwp:transport=dt_socket,address=8787,server=y,suspend=n
would be replaced with:
-agentlib:jdwp=transport=dt_socket,address=8787,server=y,suspend=n