res_pjsip: Add the ability to configure ciphers based on name.

Previously this code would only accept the OpenSSL identifier instead
of the documented name.

ASTERISK-23498 #close
ASTERISK-23498 #comment Reported by: Anthony Messina

Review: https://reviewboard.asterisk.org/r/3491/


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/12@413159 f38db490-d61c-443f-a65b-d21fe96a405b