Add description of new parallel regression testing method; update procedure to cover running either test script; other minor improvements.
Add description of new parallel regression testing method; update
procedure to cover running either test script; other minor improvements.

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