Fix some sqlite backend mistakes

[RozeFound]

1. or converts anything to boolean, so there self._connection is always True or False basically
2. Since self._connection setup only happens if user makes request, and calls store or retrieve, there always a possibility that this code won't be called, and self._connection will stay null. Which will cause exception (thanks to assert) in pretty normal scenario

[karpetrosyan]

or converts anything to boolean, so there self._connection is always True or False basically

Don't really understand this line...

Example:

>>> object() or False
<object object at 0x71b11d2e8800>

If bool(connection) is True, it takes the connection object, if not, it will create a new one.

[RozeFound]

Huh? Now that's confusing

[RozeFound]

The more you live the more you learn I guess.

[RozeFound]

What's wrong with this tests?