MT#9285 move central/pair database configs to constants

Try to use socket connection when possible

Change-Id: Ic2980ac775ff0aa3057631161798c179e8381369
MT#9373 increase kamailio.proxy.pkg_mem config value up to 32

Change-Id: I000efccb1a68c77d4210aa68ef33da6c931bf651
cfg-schema dump: snapshot Sat Oct 04 01:12:12 +0200 2014