Don't start bucardo when no syncs while testing.
Don't start bucardo when no syncs while testing.

This seems to prevent an error where Bucardo won't start, even though it
waited. I suspect this is becaust earlier tests run that start Bucardo with no
syncs and don't bother to stop it again, because they expect it to exit, as it
did prior to cc92a976e00df6a5182745b47793b44401e6b336.

Also, don't shut down Postgres on test exit. It just seems to confuse things.

ezekiel/bucardo,ezekiel/bucardo,ezekiel/bucardo