Log: cib,libcrmcommon,lrmd: handle IP addresses better in messages

This exposes lib/common/remote.c:get_ip_str() as a new internal API
crm_sockaddr2str(), and uses it wherever inet_ntoa() and inet_ntop()
were used previously.

Mainly, this reduces code duplication. It also takes cib/remote.c
one step towards supporting IPv6 addresses.