Make variable at top kamailio.cfg for interval time

[nshopik]

Currently default is 5min but some people prefer better granulation, but you have to dig into cfg file to find what need to change. So It be nice to have variable at top of config for easier management.

https://github.com/sipcapture/homer-api/blob/master/examples/sipcapture/kamailio.cfg#L459 https://github.com/sipcapture/homer-api/blob/master/examples/sipcapture/kamailio.cfg#L462

[adubovikov]

https://github.com/sipcapture/homer-api/commit/aa097505ef6aef878f97043735c64e1b5ff65c41

[nshopik]

Awesome, Thanks!