loader/main: Don't set ast_fully_booted until deferred reloads are processed

Until we have a true module management facility it's sometimes necessary for one 
module to force a reload on another before its own load is complete.  If 
Asterisk isn't fully booted yet, these reloads are deferred.  The problem is 
that asterisk reports fully booted before processing the deferred reloads which 
means Asterisk really isn't quite ready when it says it is.

This patch moves the report of fully booted after the processing of the deferred 
reloads is complete.

Since the pjsip stack has the most number of related modules, I ran the 
channels/pjsip testsuite to make sure there aren't any issues.  All tests 
passed.

Tested-by: George Joseph
Review: https://reviewboard.asterisk.org/r/4604/
........

Merged revisions 434544 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@434546 65c4cc65-6c06-0410-ace0-fbb531ad65f3