Mark SSHFP algorithm 4 as valid

Implements the unsupported records skipping fix [proposed by ross](https://github.com/github/octodns/issues/176#issuecomment-359294960) in #176 for DNSimple and additionally for NS1.

Fixes #176 and also the NS1 version of it (`AttributeError: 'Ns1Provider' object has no attribute '_data_for_DNSKEY'`) that currently affect domains that have DNSSEC enabled.

[RFC 7479](https://tools.ietf.org/html/rfc7479) introduces support for Ed25519 host keys for the SSHFP record.

Configurable geo healthcheck host & path

This will ensure unique refs for different zones. Without them the ref isn't
enough to make sure we're looking at the right thing (notably when we're
gc'ing old health checks.) This also adds a bit more debugging around health
checks.

Make the Record.octodns bits more consistent

Add twine dev requirement, use it in script/release

0.9.0 version bump and (partial) changelog updates

Make sure to insert new rulesets at the "end"

Dyn will still match them, even while they're empty before we've had a
chance to add the respons pools to them which is BAD and caused a
medium-size outage (thankfully not as bad as it could have been.) Ideally
we'd use publish=False and stage things, but that seems broken in the client
lib, there's no way to send publish=N. I also tried sending the
response_pool_ids as part of the create calls and response pool config if
one didn't exist, but neither of those routes worked :-(

Unsorted GeoValue.values can result in false diffs

Check Route 53 records against all supported types

Skip Alias recordset for Route53 Provider

Update Readme - OVH provider capabilities

Escape unescaped semicolons coming out of Google Cloud DNS

Adds a new field Plan.exists to indicate whether the zone exists

Implement populate exists for OvhProvider

* spelling: ancillary
* spelling: antarctica
* spelling: australia
* spelling: authentication
* spelling: continental
* spelling: constructor
* spelling: conversion
* spelling: creation
* spelling: doesn't
* spelling: easily
* spelling: efficiently
* spelling: equivalent
* spelling: essentially
* spelling: everything
* spelling: exactly
* spelling: be
* spelling: expensive
* spelling: supports
* spelling: healthcheck
* spelling: immediately
* spelling: ignored
* spelling: invocation
* spelling: itself
* spelling: leftovers
* spelling: missing
* spelling: natural
* spelling: nonexistent
* spelling: peculiarities
* spelling: pointing

This change hit a line length limitation, so I'm wrapping it and
adding a period which appears to match local style...

* spelling: quicker
* spelling: response
* spelling: requested
* spelling: redirect
* spelling: traffic
* spelling: unknown
* spelling: uploaded
* spelling: useful
* spelling: separately
* spelling: zone

Add DKIM to provider capabilities

Change str() to unicode() to avoid encoding problems

Fix handling of Cloudflare ALIAS updates