### Description

An error is thrown if either of these functions are not defined. The documentation states under most of the interpeters:

If this function is not defined, then Kamailio will not write error messages.

No such statement is made under `app_ruby`, however given the ethos of KEMI I presume this. is meant to be consistent.

Defining these functions with just a `return` causes the error to go away.

#### Log Messages

``` Mar 23 03:40:00 guest /usr/local/sbin/kamailio[7372]: ERROR: {2 1 INVITE 4aa920b44d1d11e98406c08c608bb89c@<IP-removed>} app_ruby [app_ruby_api.c:108]: app_ruby_print_last_exception(): exception: undefined method `ksr_reply_route' for Kernel:Module Mar 23 03:40:02 guest /usr/local/sbin/kamailio[7372]: ERROR: {1 2 BYE 4aa920b44d1d11e98406c08c608bb89c@<IP-removed>} app_ruby [app_ruby_api.c:108]: app_ruby_print_last_exception(): exception: undefined method `ksr_onsend_route' for Kernel:Module ```

### Additional Information

* **Kamailio Version** - output of `kamailio -v`

``` version: kamailio 5.3.0-dev4 (x86_64/linux) 97189d flags: STATS: Off, USE_TCP, USE_TLS, USE_SCTP, TLS_HOOKS, USE_RAW_SOCKS, DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MMAP, PKG_MALLOC, Q_MALLOC, F_MALLOC, TLSF_MALLOC, DBG_SR_MEMORY, USE_FUTEX, FAST_LOCK-ADAPTIVE_WAIT, USE_DNS_CACHE, USE_DNS_FAILOVER, USE_NAPTR, USE_DST_BLACKLIST, HAVE_RESOLV_RES ADAPTIVE_WAIT_LOOPS 1024, MAX_RECV_BUFFER_SIZE 262144, MAX_URI_SIZE 1024, BUF_SIZE 65535, DEFAULT PKG_SIZE 8MB poll method support: poll, epoll_lt, epoll_et, sigio_rt, select. id: 97189d compiled on 13:52:08 Mar 23 2019 with gcc 4.8.5 commit: 97189d7508a3946c2b3de49c178614356d816508 ```