Upgrade libstrophe and expat projects to vs2013
Fix bug with xmpp chat not connecting

The facebook suddenly stopped connecting on my dev machine. I still cannot
explain what caused this change in behaviour, but I was finally able to
diagnose and fix the problem.

Chat was not connecting due to an error in tls_start. The windows function
InitializeSecurityContext was returning a SEC_E_INCOMPLETE_MESSAGE status
which was being treated as an error. However, the documentation states
that this is not an error. This status simply indicates that more data
needs to be read. This commit does precisely that -- when
SEC_E_INCOMPLETE_MESSAGE we read more data from the socket and call
InitializeSecurityContext again.