ims: Updated example configurations

Enhancements:
- Added Ro to the S-CSCF
- Added database support, optionally use db_cluster
- Replaced RTPProxy with RTPEngine module, support for originating WebRTC on the Proxy-CSCF (with SRTP Breaking)
- Optionally engage a SBC between the P-CSCF and the Core, SEMS sample configuration
- smaller adjustments