Automate DNS creation/verification for Azure DNS

[zendern]

Currently DNS integration is a manual step for you to add the TXT entry to your DNS provider. Given some providers give you access to programmatically do so we should start to use those programmatic hooks.

Acceptance Criteria:

• We can programmatically add entry to Azure DNS
• We wait until the DNS propagation has occurred before we trigger the challenge
• We end up with a certificate that can be fully automated from start to end when using the dns challenge and configuring whatever details needed for Azure DNS integration.