pjsip cli: Change Identify to show CIDR notation instead of netmasks.

pjsip cli: Change Identify to show CIDR notation instead of netmasks.

* Added ast_sockaddr_cidr_bits() to count the 1 bits in an ast_sockaddr.
* Added ast_ha_join_cidr() which uses ast_sockaddr_cidr_bits() for the netmask
  instead of ast_sockaddr_stringify_addr.
* Changed res_pjsip_endpoint_identifier_ip to call ast_ha_join_cidr() instead
  of ast_ha_join() for the CLI output.

This is a CLI change only.  AMI was not affected.

Tested by: George Joseph
Review: https://reviewboard.asterisk.org/r/3652/
........

Merged revisions 416737 from http://svn.asterisk.org/svn/asterisk/branches/12

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@416738 65c4cc65-6c06-0410-ace0-fbb531ad65f3