Wire up Logger instance with Conf class

The actual calls needs to be implemented within the Conf class, but this
is the beginnings of adding logging support to the configuration loading
and saving processes.
Add logging support to Conf class

This is achieved mostly by extending the Cursor class implementation and
providing debug() calls for all SQL calls to the underlying database. In
addition, info() calls are done during major table operations (i.e. for
initial creation and also migration updates).
Introduce new configuration columns for debugging

Called simply, debug_file and debug_stdout, with both being off by
default.