gpinitsystem: update help usage
gpinitsystem: update help usage

- Sort arguments alphabetically
- Add -I and -O description

cjcjameson/gpdb,greenplum-db/gpdb,lisakowen/gpdb,Chibin/gpdb,ashwinstar/gpdb,jmcatamney/gpdb,janebeckman/gpdb,jmcatamney/gpdb,cjcjameson/gpdb,adam8157/gpdb,cjcjameson/gpdb,greenplum-db/gpdb,janebeckman/gpdb,kaknikhil/gpdb,ashwinstar/gpdb,jmcatamney/gpdb,janebeckman/gpdb,Quikling/gpdb,cjcjameson/gpdb,kaknikhil/gpdb,janebeckman/gpdb,kaknikhil/gpdb,Quikling/gpdb,50wu/gpdb,edespino/gpdb,Quikling/gpdb,edespino/gpdb,xinzweb/gpdb,edespino/gpdb,Chibin/gpdb,xinzweb/gpdb,xinzweb/gpdb,lisakowen/gpdb,Chibin/gpdb,greenplum-db/gpdb,Chibin/gpdb,lisakowen/gpdb,cjcjameson/gpdb,xinzweb/gpdb,ashwinstar/gpdb,edespino/gpdb,edespino/gpdb,kaknikhil/gpdb,jmcatamney/gpdb,edespino/gpdb,jmcatamney/gpdb,kaknikhil/gpdb,50wu/gpdb,yuanzhao/gpdb,yuanzhao/gpdb,yuanzhao/gpdb,ashwinstar/gpdb,lisakowen/gpdb,xinzweb/gpdb,adam8157/gpdb,Chibin/gpdb,edespino/gpdb,Quikling/gpdb,lisakowen/gpdb,adam8157/gpdb,50wu/gpdb,cjcjameson/gpdb,Quikling/gpdb,yuanzhao/gpdb,ashwinstar/gpdb,50wu/gpdb,yuanzhao/gpdb,greenplum-db/gpdb,adam8157/gpdb,Chibin/gpdb,xinzweb/gpdb,greenplum-db/gpdb,cjcjameson/gpdb,cjcjameson/gpdb,Quikling/gpdb,jmcatamney/gpdb,janebeckman/gpdb,Chibin/gpdb,jmcatamney/gpdb,janebeckman/gpdb,Chibin/gpdb,lisakowen/gpdb,cjcjameson/gpdb,janebeckman/gpdb,janebeckman/gpdb,ashwinstar/gpdb,lisakowen/gpdb,edespino/gpdb,Quikling/gpdb,Quikling/gpdb,50wu/gpdb,edespino/gpdb,lisakowen/gpdb,50wu/gpdb,yuanzhao/gpdb,ashwinstar/gpdb,Quikling/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,yuanzhao/gpdb,janebeckman/gpdb,Quikling/gpdb,greenplum-db/gpdb,kaknikhil/gpdb,adam8157/gpdb,xinzweb/gpdb,xinzweb/gpdb,yuanzhao/gpdb,janebeckman/gpdb,adam8157/gpdb,50wu/gpdb,50wu/gpdb,adam8157/gpdb,cjcjameson/gpdb,yuanzhao/gpdb,kaknikhil/gpdb,Chibin/gpdb,kaknikhil/gpdb,ashwinstar/gpdb,adam8157/gpdb,Chibin/gpdb,edespino/gpdb,jmcatamney/gpdb,kaknikhil/gpdb,kaknikhil/gpdb,yuanzhao/gpdb