res_pjsip_config_wizard: Cleanup load unload

res_pjsip_config_wizard: Cleanup load unload

While investigating other unload issues I realized that the load/unload process
for the config wizard was pretty ugly so I've refactored it as follows...

When the res_pjsip sorcery instance is created the config_wizard bumps it's own
module reference to prevent it from unloading while the sorcery instance is
still active.  When res_pjsip unloads and it's sorcery instance is destroyed,
the config wizard unrefs itself which then allows itself to unload cleanly.
Since the config wizard now can't load after res_pjsip or unload before it
(which should have been the correct behavior all along), I was able to remove
the chunks of code in both load_module and unload_module that handled that case.

Ran the testsuite tests to insure there were no functional changes and REF_DEBUG
to insure that Asterisk was shutting down cleanly with no FRACKs or leaks.

Tested-by: George Joseph
Review: https://reviewboard.asterisk.org/r/4610/

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/13@434619 65c4cc65-6c06-0410-ace0-fbb531ad65f3