Enhance gpsegwalrep.py to support full recovery.
Enhance gpsegwalrep.py to support full recovery.

Mostly re-used init-mirrors for this functionality.

Author: Ashwin Agrawal <924bf3437ad315c1c74f9c41d83153600b05f548@pivotal.io>
Author: Taylor Vesely <2e71e1faa215a6c19636ce18fd58ddc16fff98ae@pivotal.io>

50wu/gpdb,edespino/gpdb,greenplum-db/gpdb,edespino/gpdb,adam8157/gpdb,adam8157/gpdb,ashwinstar/gpdb,lisakowen/gpdb,edespino/gpdb,50wu/gpdb,jmcatamney/gpdb,Chibin/gpdb,50wu/gpdb,xinzweb/gpdb,ashwinstar/gpdb,Chibin/gpdb,adam8157/gpdb,xinzweb/gpdb,xinzweb/gpdb,edespino/gpdb,jmcatamney/gpdb,edespino/gpdb,ashwinstar/gpdb,ashwinstar/gpdb,edespino/gpdb,greenplum-db/gpdb,lisakowen/gpdb,ashwinstar/gpdb,edespino/gpdb,jmcatamney/gpdb,jmcatamney/gpdb,ashwinstar/gpdb,lisakowen/gpdb,xinzweb/gpdb,greenplum-db/gpdb,lisakowen/gpdb,xinzweb/gpdb,jmcatamney/gpdb,jmcatamney/gpdb,jmcatamney/gpdb,50wu/gpdb,adam8157/gpdb,greenplum-db/gpdb,lisakowen/gpdb,Chibin/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,adam8157/gpdb,edespino/gpdb,adam8157/gpdb,edespino/gpdb,50wu/gpdb,xinzweb/gpdb,xinzweb/gpdb,lisakowen/gpdb,Chibin/gpdb,adam8157/gpdb,Chibin/gpdb,Chibin/gpdb,xinzweb/gpdb,50wu/gpdb,ashwinstar/gpdb,jmcatamney/gpdb,Chibin/gpdb,greenplum-db/gpdb,lisakowen/gpdb,50wu/gpdb,greenplum-db/gpdb,Chibin/gpdb,50wu/gpdb,Chibin/gpdb,edespino/gpdb,adam8157/gpdb,ashwinstar/gpdb,Chibin/gpdb,lisakowen/gpdb