Sorcery: Log when old config remains in use

This adds a log message notifying the user that a stale configuration
is in place upon reload when a config object fails to load. This
situation can end up causing confusion when the object failed to load
but exists from a previous config load especially when the old config
is significantly different from the new config.

Review: https://reviewboard.asterisk.org/r/4250/
Reported by: Thomas Thompson
........

Merged revisions 429429 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/13@429430 f38db490-d61c-443f-a65b-d21fe96a405b