start-server: respect $MAVEN_OPTS, if set

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>
osgi: make all servlet routes start with /

Register all OSGI servlets under a proper absolute path.
Without it, the new servlet routing scheme was broken for JRuby plugins.

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>
osgi: make the killbill ServiceListener more flexible

Don't look for an exact class, allow subclasses as well.

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>