Add support for Cloudflare API Token replacing legacy API Key

[thekordy]

As stated here: https://developers.cloudflare.com/fundamentals/api/get-started/keys/

Global API key is the previous authorization scheme for interacting with the Cloudflare API. When possible, use API tokens instead of Global API key.

This small pull request will add support for users to use Cloudflare API tokens instead of email+API Key (which could also solve the problem stated here #302 ) that is more secured settings than entering the global API key.

As a result, only API token is needed, users won't need to set their Cloudflare email.

set the config

ee config set cloudflare-api-token <cf-api-token>

renew SSL

ee site ssl-renew <site-name>