Fixes#634
The Django import system seems to produce errors
in certain configurations and especially when
MIGRATION_MODULES configuration is set globally.
This is most probably caused by misbehaving or cyclic
Python module imports in the Django application
instrumentatation chain that come up when the
MIGRATION_MODULES configuration is altered.
This patch migrates to the standard Python logging system
use and has less overhead and complexity for users as well.
Having a configurable logging prefix does not produce
a lot of benefits and is less flexible than having
all individual module logging configurations accessible
through the module __name__ parameter in Axes.
For example axes.handlers.* or axes.backends.*
are separately configurable in the new scheme
whereas they would have been both bundled under
the AXES_LOGGER log configuration.
