* Implement a lookup mechanism that monitors the A record of hostnames in
   the configuration and don't use the Hostname datatype since it does a
   lookup when parsing the configuration file which might fail due to a
   temporary glitch.
 * Increase robustness by not failing with a weird error message ("list index
   out of range") when there are no connections to the rating engine.
 * Implement support for DebitBalance for SIP MESSAGE (SMS)