res_pjsip_outbound_registration: Fix several reload issues

res_pjsip_outbound_registration: Fix several reload issues

There are 2 issues with reloading registrations...

1.  The 'can_reuse_registration' test wasn't considering the intervals or
expiration in its determination of whether a registration changed or not so if
you changed any of the intervals or the expiration and reloaded, the object
would get reloaded but the actual timers wouldn't change.
can_reuse_registration now does a sorcery diff on the old and new objects
instead of discretely testing certain fields.  Now if you change expiration for
instance, and reload, the timer is updated and re-registration will occur on the
new value.

2.  If you mung up your password on an outbound registration you get a permanent
failure.  If you fix the password (on the outbound_auth object) and reload,
nothing tells outbound_registration to try again because the registration itself
didn't change.  This patch adds an observer on the "auth" object type and if any
auth changes, existing registration states are searched and those in a
REJECTED_PERMANENT state are retried.

Tested-by: George Joseph
Review: https://reviewboard.asterisk.org/r/4304/
........

Merged revisions 430373 from http://svn.asterisk.org/svn/asterisk/branches/13

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@430374 65c4cc65-6c06-0410-ace0-fbb531ad65f3