OpenSSL TLS contexts assume ownership of any additional certificate
passed into it. The CertificateFactory now returns a vector of
unique_ptrs, and OpenSSLContext will do the needful with releasing
ownership at the right moment.
A unit test has been added that uses a chained certificate in
client/server context. Before the fix, this test would either fail, or
result in a segmentation fault, depending on the mood of OpenSSL.
Unit tests pass on Debian 9
Ran manual tests with server test code, tested both chained and single
certificates, and no longer observed crashes when accepting a