Fix set ca_file twice, no SSL for Rails.env.test

Hard coding this check for Rails.env.test? isn't ideal. I need to look into
getting the cacert.pem on the CI server itself.
Set default API version to v2
Don't version control .gem files
Bump api version in readme to v2
Check for Rails before trying to get the env
Remove the old example.rb and add examples/ folder

These show the usage for creating an envelope from a document both via
the gem, and via a raw NET::HTTP::Post request