pjsip cli: Fix sorting of contacts for 'pjsip list contacts'

For some reason I was using a hash container instead of a list to gather the
contacts for 'pjsip list/show contacts' so even though I had a sort function,
the output wasn't sorted.  This patch just changes the hash container to a
list container and the contacts now appear sorted in the CLI.

Tested-by: George Joseph

Review: https://reviewboard.asterisk.org/r/4305/
........

Merged revisions 430221 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@430222 65c4cc65-6c06-0410-ace0-fbb531ad65f3