Auto-reconnect to mongo database

I wish I knew this option existed ~7yr ago.  This should have been
done long ago, but we've had so few problems with it, that it had
never been explored.

This [version of this] mongo library is ancient and needs to be
upgraded.  Until then, this'll do.

* src/server/daemon/controller.js (init): Set `auto_reconnect'.

src/server/daemon/controller.js

@@ -103,7 +103,7 @@ exports.init = function( logger, enc_service )
         new MongoServer(
             process.env.MONGODB_HOST || '127.0.0.1',
                 +process.env.MONGODB_PORT || MongoConnection.DEFAULT_PORT,
-            {}
+            { auto_reconnect: true }
         ),
         { native_parser: false, safe: false }
     );