Bug 1079361 - Postgres Plugin - Scheduling A New List Process Statistics Operation Fails

The execution of this operation involves a query on the pg_stat_activity view, which format has changes in 9.2 (see http://wiki.postgresql.org/wiki/What%27s_new_in_PostgreSQL_9.2#pg_stat_activity_and_pg_stat_replication.27s_definitions_have_changed)

Now the server plugin component adapts the query depending on the Postgres server version

(cherry picked from commit 78cf9729cb74923a37d98c0d2b51063b23871243)