Use service postgresql initdb with el6

postgresql-setup does not exists on el6,
the service postgresql initdb is the documented db init command.

Change-Id: I2b92a3c8e7db603eb13378e46893fc81f507405b
diff --git a/lib/databases/postgresql b/lib/databases/postgresql
index 60e5a33..c459feb 100644
--- a/lib/databases/postgresql
+++ b/lib/databases/postgresql
@@ -43,7 +43,13 @@
     if is_fedora; then
         PG_HBA=/var/lib/pgsql/data/pg_hba.conf
         PG_CONF=/var/lib/pgsql/data/postgresql.conf
-        sudo [ -e $PG_HBA ] || sudo postgresql-setup initdb
+        if ! sudo [ -e $PG_HBA ]; then
+            if ! [[ $DISTRO =~ (rhel6) ]]; then
+                sudo postgresql-setup initdb
+            else
+                sudo service postgresql initdb
+            fi
+        fi
     elif is_ubuntu; then
         PG_DIR=`find /etc/postgresql -name pg_hba.conf|xargs dirname`
         PG_HBA=$PG_DIR/pg_hba.conf