### Description
ACC module allows setting datetime fields in UTC via [time_mode param](http://kamailio.org/docs/modules/devel/modules/acc.html#acc.p.time_mode).
However, this setting does not cause cdr entries to be saved in that format and I haven't found any equivalent parameter to achieve this.
### Troubleshooting
Analyzing the code for MySQL database storage I have found that [_db_time2str_ex_ function defined in _db_ut.c_](https://github.com/kamailio/kamailio/blob/master/src/lib/srdb1/db_ut.c#L256) uses localtime().
### Possible Solutions
Changing localtime() to gmtime() cdrs are saved in UTC, but it would be desirable to add a new module param that makes this configurable.
### Additional Information
* **Kamailio Version** - output of `kamailio -v`
``` version: kamailio 4.4.6 (x86_64/linux) 0a8379-dirty flags: STATS: Off, USE_TCP, USE_TLS, USE_SCTP, TLS_HOOKS, DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MEM, 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_LISTEN 16, MAX_URI_SIZE 1024, BUF_SIZE 65535, DEFAULT PKG_SIZE 8MB poll method support: poll, epoll_lt, epoll_et, sigio_rt, select. id: 0a8379 -dirty compiled on 17:01:42 Dec 4 2017 with gcc 6.3.0
```
* **Operating System**:
<!-- Details about the operating system, the type: Linux (e.g.,: Debian 8.4, Ubuntu 16.04, CentOS 7.1, ...), MacOS, xBSD, Solaris, ...; Kernel details (output of `uname -a`) -->
``` Linux 4.9.0-3-amd64 #1 SMP Debian 4.9.30-2+deb9u3 (2017-08-06) x86_64 GNU/Linux ```
Should I proceed and try to get a working PR to add this new modparam or there is currently a way to get this that I have missed (apart from setting system time to UTC)?
Thank you and regards,