logging: remove object-specific loggers

Remove all object-specific loggers, with the exception of `Plugin.log`,
which is now deprecated. Replace affected logger calls with module-level
logger calls.

Deprecate object-specific loggers in `ipa_log_manager.get_logger`.

Reviewed-By: Martin Basti <mbasti@redhat.com>

ipaserver/plugins/session.py

@@ -2,10 +2,14 @@
 # Copyright (C) 2015  FreeIPA Contributors see COPYING for license
 #
 
+import logging
+
 from ipalib import Command
 from ipalib.request import context
 from ipalib.plugable import Registry
 
+logger = logging.getLogger(__name__)
+
 register = Registry()
 
 
@@ -19,7 +23,7 @@ class session_logout(Command):
     def execute(self, *args, **options):
         ccache_name = getattr(context, 'ccache_name', None)
         if ccache_name is None:
-            self.debug('session logout command: no ccache_name found')
+            logger.debug('session logout command: no ccache_name found')
         else:
             delattr(context, 'ccache_name')