Mostly works, but doesn't yet dump out the values

Refactors the provider class lookup and kwarg processing so that it can be
reused for plan_output.

migrate from pep8 to pycodestyle #152

Transform @ in Digitalocean API values to zone name

Add DigitalOcean provider

remove default config file for octodns-validate

Add formal CAA support to YamlProvider

adds an example of how to setup geodns to the docs

Improve setuptools capabilities

Make PowerDnsBaseProvider's timeout configurable

fix error on version

adding minimal version only for contributors

define 3 kinds of requirements (base, dev, test)
retrieve version from __init__.py
define setuptools minimal version

in CI install full (base, dev, test) dependencies

OVH: Add support of DKIM records

Add support for included and excluded records

Improve Validations for None/Empty values, Ignore None/Empty values during dump

dump does not write invalid value(s) to yaml

Allow enabling lenient on a per-record basis with octodns.lenient

set default value for nsone cname to None, use first value if non-zer…

```
---
'':
    octodns:
        ignored: True
        lenient: True
    type: CNAME # not valid to have a root cname
    value: foo.com.