Updates Squarespace configuration

[sbastn]

This PR fixes #87:

1. Deprecates existing Squarespace6 configuration. We cannot change the name of a service, so this is why I am deprecating it.
2. Adds new configuration for Squarespace.

🔍 Verification steps

1. Point your local configuration to this branch. In your app, edit lib/tasks/services.rake to change the source where to load one-click services.

# sh("git clone git@github.com:dnsimple/dnsimple-services.git tmp/dnsimple-services")
sh("git clone ~/projects/dnsimple/dnsimple-services tmp/dnsimple-services")

2. In the app, run the task rake services:load

3. Verify that you see the service for Squarespace. Squarespace 6 shouldn't be visible.

4. Apply the service. It should create 3 records:

5. Verify that these are the expected records specified by Squarespace: https://support.squarespace.com/hc/en-us/articles/205812378

[san983]

✅ LGTM!

I was going to ask about the A records instead the ALIAS that appears in https://support.squarespace.com/hc/en-us/articles/205812378. But read about @OleMchls' test in #87 (comment) 👏