KAZOO-1093: generic ETS table manager
KAZOO-1093: omnipresence subscription manager
KAZOO-1093: log the stacktrace properly
KAZOO-1093: start to handle subscription requests
KAZOO-1093: update formatting, tickies
KAZOO-1093: update tickies, formatting
KAZOO-1093: wapi module to handle kamailio presence-related APIs