Quick-fix disable ALIAS for Route53 & Cloudflare

Cloudflare could potentially support it, but their details are different enough
that i'll need to be looked into specifically later.

Skip planning (and populating) zones without elible targets

docs: Fix small typos

Alias support

Add support for ignored records.

Escape unescaped semicolons coming out of Route53

Fix zone-level always-dry-run functionality

Thanks @offmindby!

```yaml
ignored:
  octodns:
    ignored: true
  type: A
  value: 1.2.3.4
```

DnsimpleProvider updates delete before create, or else errors thrown

NS1 does not support SSHFP

Supports ALIAS for Dnsimple, Dyn, Ns1, and PowerDNS. Notes added to readme about
some of the quirks found while working with them. TTL seems to mostly be
accepted on ALIAS records so it has been added back, what it means seems to vary
across providers, thus notes.

Fix NS1 provider name

Update example class name from "octodns.provider.nsone.Ns1Provider" to working "octodns.provider.ns1.Ns1Provider".

Update README to include new NS1 Provider

First pass through NsOneProvider

Add __main__ calls to main in cmds

Fixing octodns/record.py link

use a percentage of change/deleted records rather than an absolute count