notifier: resource leak using all available db connections

Only initialize the data source once instead of each event loop,
preventing existing connections from being orphaned.

Change-Id: Ib7db8bdd66ca8f6412b1ef709c141b0b97dffbfb
Bug-Url: https://bugzilla.redhat.com/905709
Signed-off-by: Greg Padgett <gpadgett@redhat.com>