Allow TLSv1 protocol by default

The current settings means httpclient will only do SSLv3 protocol. Using
the SSLv23 actually means trying to find the a working one including
TLSv1. For more details see:

http://www.openssl.org/docs/ssl/SSL_CTX_new.html

Here's also information on the same topic:

http://stackoverflow.com/questions/11059059/is-it-possible-to-enable-tls-v1-2-in-ruby-if-so-how