Start script of JOC's Jetty Web Server should consider JAVA_HOME environment variable

s3. Current Situation

• The start script provided by Jetty uses an environment variable $JAVA if you want to start Jetty with a specific Java.
• It doesn't have an effect to set $JAVA_HOME.

Desired Behavior

The installer of JOC should set $JAVA with $JAVA_HOME/bin/java as a default for Jetty if $JAVA_HOME is set in

• /etc/default/joc (by installation with root permissions)
• ~/.jocrc (by installation without root permissions)

which are sourced by the start script.