Use SSL_OP_NO_COMPRESSION if possible

Use SSL_OP_NO_COMPRESSION if OpenSSL library supports it instead of
clearing compression methods stack.
Support for DH parameters file

DH parameters are required for DH key exchange providing forward
secrecy. While ECDH is a better alternative, older clients don't
support ECDH, while DH support is fairly common.
DH parameters are stored in a file and can be generated by openssl:
dhparam -out dhparams 1024
Use proper #ifndef for ECDH (OPENSSL_NO_ECDH instead of OPENSSL_NO_EC)
Merge pull request #102 from rraptorr/tls

Small TLS improvements