update httpclient gem version

httpclient gem needs to be 2.4 or higher, otherwise it will default to using SSLv3 which makes you vulnerable to POODLE attacks. I was getting issues with an app because of gems we are using (namely Faraday) seem to dislike SSLv3 because of this vulnerability. I couldn't update the httpclient version because of the lock you have in place.

I also strongly suggest that the next version of this rets client should REQUIRE 2.4 or higher because of POODLE