OFConnectionManager: use proto_ip_string in CXN_FMT
OFConnectionManager: factor out ind_cxn_parse_sockaddr
OFConnectionManager: create sockets with correct family
OFConnectionManager: support IPv6
OFConnectionManager: parse IP addresses with getaddrinfo

This function supports IPv6 link-local addresses by letting you add a '%'
followed by the interface name.
OFConnectionManager: populate IPv6 URIs in controller connections list
OFConnectionManager: decrease string buffer sizes
OFConnectionManager: get sockaddr_storage from the system header
Merge into master from pull request #164:
support IPv6 in OFConnectionManager (https://github.com/floodlight/indigo/pull/164)