Adds fix for ssl negotiation to braintree

      Implements the suggestion as given here:
      https://groups.google.com/forum/?fromgroups=#!topic/activemerchant/SZgiVs6bUmI
      
      This fixes Ubuntu 12.04 + OpenSSL 1.0.1c + Ruby 1.8/1.9 not being able to talk to the braintree gateway.
      There is a ssl type negotiation issue:
      curl https://secure.braintreepaymentgateway.com/api/transact.php # Fails
      curl -I --sslv3 https://secure.braintreepaymentgateway.com/api/transact.php # Succeeds