R1:80b75a5f3bdd

Provide connection isolation to Lisk and enable it by default in tests

Summary:
Allow Lisk to be put into process-isolated mode which establishes
only isolated connections. By default, put it into this mode when running
unit tests. Build some simple unit tests around object insertion and
updating.

NOTE: The one flaw in this is that $dao->establishConnection() still
punches through the isolation layer. I need to do an API change to fix this
though so I'm holding it for now. It will probably just rename…