High: postgres-8: Shutdown postgres with SIGINT before forcing SIGQUIT

SIGINT should be attempted shutdown the postgres server before
issuing a SIGQUIT to force the shutdown.  The shutdown signals
are documented here.
http://www.postgresql.org/docs/8.4/static/server-shutdown.html

Resolves: rhbz#871659
Merge pull request #248 from davidvossel/bz871659

High: postgres-8: Shutdown postgres with SIGINT before forcing SIGQUIT