added fifo option

ser.cfg

@@ -4,6 +4,7 @@ dns=on           # (cmd. line: -r)
 rev_dns=yes      # (cmd. line: -R)
 fork=no          # (cmd. line: -D)
 log_stderror=yes # (cmd line: -E)
+fifo=/tmp/ser_fifo
 # for more info: sip_router -h