Add ircbouncer required vars to group_vars/sovereign

group_vars/sovereign

 # --------
 # common_timezone will be used in the common and mailserver roles
 # common_timezone: 'Etc/UTC'
+
+# znc
+# ---
+# irc_nick: (required)
+# irc_ident: (required)
+# irc_realname: (required)
+# irc_quitmsg: (required)
+# irc_password_hash: (required)
+# irc_password_salt: (required)