Add support for certificate chains.

Add options (--ssl-chain-cert and --no-ssl-chain-cert) to control whether the argument to --ssl-cert is treated as a single certificate or a chain of certificates down to the root CA certificate.  Chained certificates are required by some browsers, including Firefox, in order to recognize some certificates.
Merge pull request #52 from ryantrinkle/0.9-stable

Add support for certificate chains.