Attempt to use sessions only when they are enabled
Properly initialize logging

We need to call APLOG_USE_MODULE() so that the module name is reported
properly in log lines, and per module logging level can be set.

Fixes #6
Fix build on some platforms by adding extra flags

For some reason all the necessary CFALGS are not returned by simply
querying the CFLAGS from apxs. We also need to query EXTRA_CPPFLAGS
apparently.
Fix error message copy&paste error
Bump version to 1.0.4