[WFLY-2261] Fix standalone.sh --debug [<port>]
[WFLY-2261] Fix standalone.sh --debug [<port>]

Fix standalone.sh script when the debug port is specified on the command
line.

WildFly's server Main class expects to get --debug from its args before
the debug port. Add it to the script's $SERVER_OPTS if debug mode is
set.

JIRA: https://issues.jboss.org/browse/WFLY-2261

iweiss/wildfly,xasx/wildfly,99sono/wildfly,pferraro/wildfly,wildfly/wildfly,tadamski/wildfly,jstourac/wildfly,iweiss/wildfly,pferraro/wildfly,tomazzupan/wildfly,golovnin/wildfly,iweiss/wildfly,rhusar/wildfly,wildfly/wildfly,jstourac/wildfly,tomazzupan/wildfly,99sono/wildfly,tomazzupan/wildfly,xasx/wildfly,golovnin/wildfly,wildfly/wildfly,tadamski/wildfly,xasx/wildfly,wildfly/wildfly,iweiss/wildfly,pferraro/wildfly,jstourac/wildfly,rhusar/wildfly,jstourac/wildfly,tadamski/wildfly,golovnin/wildfly,pferraro/wildfly,rhusar/wildfly,rhusar/wildfly,99sono/wildfly