Implement user-defined SSL Ciphers and TLS version

In order to acquire better tactical speed against possibly censorship actions based on SSL Ciphers and/or TLS version fingerprint, this ticket propose to make them configurable.

The default Torrc would include the default SSL Ciphers configuration and TLS version support.

The SSL ciphers configuration should be:

• SSL Cipher List
• SSL Cipher Order
• SSL/TLS Version supported

The configuration should follow the parameters defined by OpenSSL http://www.openssl.org/docs/apps/ciphers.html .