Adding Octodns provider class for easyDNS

* Removed conversion of DYN records to A records
* Updated test fixtures to change test DYN to an A record

* Removed conversion of URL and STEALTH records to CNAME records
* Updated test fixtures to remove URL conversion testing

Add support for wildcard SRV records, as shown in RFC 2782

Cloudflare: Increase page size

fix: dependency 'ipaddress' unnecessary for py >= 3.2

Also corrects futures to 3.2 in requires

* Replaced camelCase with snake_case
* Change apikey to api_key
* Added check on record name before delete during domain_create

Adding environment variable record injection

Per the discussion on https://github.com/github/octodns/issues/583
here is a work in progress of environment variable injection for
discussion.

Ultradns support

Also some comment additions

Avoid escaping semicolon in Selectel DNS

Root NS modification support is being developed on
https://github.com/github/octodns/pull/434

Removing attempts to validate this functionality for now.

Fix issue caused by making changes to the README.md through IDE which
appears to have incorrectly encoded some of the lines that were not
changed to add the EasyDNS provider details.

This provider class for easydns.com adds support for basic dns records
through the easyDNS v3 API.  Support for dynamic and geo based dns
records is planned for a future update.

Sample configuration for the easyDNS provider are:

  easydns:
     class: octodns.provider.easydns.EasyDNSProvider
     token: <token>
     apikey: <key>

The token and key values are found on the easyDNS customer portal at:

https://cp.easydns.com/manage/security/api/production_info.php

Also, below are some optional configuration parameters which can be
added to override the class defaults.  By default the provider class
connects with the LIVE easyDNS API, if you wish to perform testing
with the easyDNS Sandbox API you can enable it by adding the following
configuration parameter:

     sandbox: True

Note, the API token and key are different for the sandbox than they
are for the production API, you can obtain sandbox credentials at:

https://cp.easydns.com/manage/security/api/sandbox_info.php

Lastly, if you have created Domain Portfolios through the easyDNS CP
you can configure which portfolio new domains will be added to by
supplying the portfolio option with the name of your portfolio.

     portfolio: <portfolio name>

Add healthcheck option 'request_interval' for Route53 provider