Add single-letter encryption options for createuser.  Update createuser --help.
Add single-letter encryption options for createuser.  Update createuser --help.

CraigHarris/gpdb,greenplum-db/gpdb,arcivanov/postgres-xl,lintzc/gpdb,randomtask1155/gpdb,snaga/postgres-xl,kaknikhil/gpdb,Postgres-XL/Postgres-XL,adam8157/gpdb,chrishajas/gpdb,ashwinstar/gpdb,yuanzhao/gpdb,jmcatamney/gpdb,atris/gpdb,oberstet/postgres-xl,yuanzhao/gpdb,Chibin/gpdb,zaksoup/gpdb,rubikloud/gpdb,chrishajas/gpdb,ovr/postgres-xl,kaknikhil/gpdb,janebeckman/gpdb,tpostgres-projects/tPostgres,foyzur/gpdb,lintzc/gpdb,randomtask1155/gpdb,ahachete/gpdb,CraigHarris/gpdb,jmcatamney/gpdb,rvs/gpdb,cjcjameson/gpdb,zaksoup/gpdb,snaga/postgres-xl,tangp3/gpdb,cjcjameson/gpdb,postmind-net/postgres-xl,techdragon/Postgres-XL,randomtask1155/gpdb,zeroae/postgres-xl,royc1/gpdb,royc1/gpdb,lisakowen/gpdb,0x0FFF/gpdb,jmcatamney/gpdb,kaknikhil/gpdb,zeroae/postgres-xl,ahachete/gpdb,snaga/postgres-xl,lintzc/gpdb,lisakowen/gpdb,lisakowen/gpdb,kaknikhil/gpdb,xinzweb/gpdb,tangp3/gpdb,edespino/gpdb,snaga/postgres-xl,kmjungersen/PostgresXL,greenplum-db/gpdb,CraigHarris/gpdb,yazun/postgres-xl,rvs/gpdb,yuanzhao/gpdb,Postgres-XL/Postgres-XL,Chibin/gpdb,zeroae/postgres-xl,xuegang/gpdb,edespino/gpdb,Postgres-XL/Postgres-XL,edespino/gpdb,xuegang/gpdb,Chibin/gpdb,Quikling/gpdb,jmcatamney/gpdb,atris/gpdb,kaknikhil/gpdb,oberstet/postgres-xl,chrishajas/gpdb,cjcjameson/gpdb,adam8157/gpdb,ahachete/gpdb,CraigHarris/gpdb,50wu/gpdb,Quikling/gpdb,atris/gpdb,royc1/gpdb,kaknikhil/gpdb,xuegang/gpdb,Quikling/gpdb,cjcjameson/gpdb,Chibin/gpdb,tangp3/gpdb,ashwinstar/gpdb,lisakowen/gpdb,lpetrov-pivotal/gpdb,rubikloud/gpdb,lisakowen/gpdb,zaksoup/gpdb,Quikling/gpdb,janebeckman/gpdb,Quikling/gpdb,CraigHarris/gpdb,CraigHarris/gpdb,kmjungersen/PostgresXL,Postgres-XL/Postgres-XL,Quikling/gpdb,jmcatamney/gpdb,ahachete/gpdb,edespino/gpdb,janebeckman/gpdb,50wu/gpdb,xuegang/gpdb,chrishajas/gpdb,royc1/gpdb,zaksoup/gpdb,arcivanov/postgres-xl,edespino/gpdb,oberstet/postgres-xl,yuanzhao/gpdb,50wu/gpdb,royc1/gpdb,yuanzhao/gpdb,ashwinstar/gpdb,lisakowen/gpdb,xinzweb/gpdb,yazun/postgres-xl,xinzweb/gpdb,adam8157/gpdb,lpetrov-pivotal/gpdb,cjcjameson/gpdb,zeroae/postgres-xl,postmind-net/postgres-xl,xinzweb/gpdb,foyzur/gpdb,Quikling/gpdb,techdragon/Postgres-XL,jmcatamney/gpdb,jmcatamney/gpdb,zaksoup/gpdb,chrishajas/gpdb,0x0FFF/gpdb,xuegang/gpdb,ashwinstar/gpdb,rubikloud/gpdb,tangp3/gpdb,royc1/gpdb,rvs/gpdb,lintzc/gpdb,postmind-net/postgres-xl,yuanzhao/gpdb,adam8157/gpdb,royc1/gpdb,lintzc/gpdb,lpetrov-pivotal/gpdb,lintzc/gpdb,cjcjameson/gpdb,zaksoup/gpdb,atris/gpdb,kmjungersen/PostgresXL,adam8157/gpdb,tpostgres-projects/tPostgres,rubikloud/gpdb,lpetrov-pivotal/gpdb,janebeckman/gpdb,50wu/gpdb,yazun/postgres-xl,techdragon/Postgres-XL,tpostgres-projects/tPostgres,rvs/gpdb,edespino/gpdb,0x0FFF/gpdb,randomtask1155/gpdb,foyzur/gpdb,adam8157/gpdb,pavanvd/postgres-xl,randomtask1155/gpdb,randomtask1155/gpdb,janebeckman/gpdb,Chibin/gpdb,tpostgres-projects/tPostgres,Chibin/gpdb,rvs/gpdb,Quikling/gpdb,tangp3/gpdb,lintzc/gpdb,0x0FFF/gpdb,edespino/gpdb,yuanzhao/gpdb,adam8157/gpdb,yuanzhao/gpdb,ahachete/gpdb,lisakowen/gpdb,CraigHarris/gpdb,lisakowen/gpdb,50wu/gpdb,pavanvd/postgres-xl,janebeckman/gpdb,janebeckman/gpdb,xuegang/gpdb,janebeckman/gpdb,rvs/gpdb,foyzur/gpdb,lpetrov-pivotal/gpdb,arcivanov/postgres-xl,oberstet/postgres-xl,foyzur/gpdb,edespino/gpdb,0x0FFF/gpdb,0x0FFF/gpdb,tangp3/gpdb,ovr/postgres-xl,xinzweb/gpdb,pavanvd/postgres-xl,rvs/gpdb,chrishajas/gpdb,0x0FFF/gpdb,zaksoup/gpdb,yazun/postgres-xl,greenplum-db/gpdb,arcivanov/postgres-xl,rvs/gpdb,greenplum-db/gpdb,cjcjameson/gpdb,rvs/gpdb,ahachete/gpdb,rubikloud/gpdb,xinzweb/gpdb,lintzc/gpdb,kaknikhil/gpdb,Chibin/gpdb,CraigHarris/gpdb,yazun/postgres-xl,ashwinstar/gpdb,foyzur/gpdb,tangp3/gpdb,xuegang/gpdb,Quikling/gpdb,greenplum-db/gpdb,arcivanov/postgres-xl,ahachete/gpdb,xuegang/gpdb,Chibin/gpdb,Quikling/gpdb,xinzweb/gpdb,ashwinstar/gpdb,Chibin/gpdb,rvs/gpdb,tpostgres-projects/tPostgres,atris/gpdb,ovr/postgres-xl,xinzweb/gpdb,0x0FFF/gpdb,lpetrov-pivotal/gpdb,atris/gpdb,randomtask1155/gpdb,techdragon/Postgres-XL,snaga/postgres-xl,chrishajas/gpdb,yuanzhao/gpdb,janebeckman/gpdb,zaksoup/gpdb,edespino/gpdb,zeroae/postgres-xl,rubikloud/gpdb,edespino/gpdb,ashwinstar/gpdb,50wu/gpdb,lpetrov-pivotal/gpdb,foyzur/gpdb,Chibin/gpdb,50wu/gpdb,kaknikhil/gpdb,rubikloud/gpdb,rubikloud/gpdb,ovr/postgres-xl,cjcjameson/gpdb,techdragon/Postgres-XL,greenplum-db/gpdb,greenplum-db/gpdb,chrishajas/gpdb,CraigHarris/gpdb,ahachete/gpdb,cjcjameson/gpdb,arcivanov/postgres-xl,jmcatamney/gpdb,lintzc/gpdb,atris/gpdb,cjcjameson/gpdb,pavanvd/postgres-xl,kmjungersen/PostgresXL,oberstet/postgres-xl,Postgres-XL/Postgres-XL,ashwinstar/gpdb,randomtask1155/gpdb,postmind-net/postgres-xl,lpetrov-pivotal/gpdb,greenplum-db/gpdb,pavanvd/postgres-xl,50wu/gpdb,xuegang/gpdb,atris/gpdb,royc1/gpdb,foyzur/gpdb,kmjungersen/PostgresXL,adam8157/gpdb,yuanzhao/gpdb,tangp3/gpdb,postmind-net/postgres-xl,kaknikhil/gpdb,janebeckman/gpdb,kaknikhil/gpdb,ovr/postgres-xl