Make sure server SSL certificate is also validated when using older versions of
cuRL by setting CURLOPT_SSL_VERIFYPEER to 1.

For explicitness sake, also explicity set CURLOPT_SSL_VERIFYHOST option
to a default value of 2.
Include module version in the User-Agent header.
Update readme.
Merge pull request #57 from Kami/specify_curl_ssl_options_update_readme

Force older versions of cURL to verify server SSL certificate, update readme, add module version to the User-Agent header