Use GlobalTables, add DNS for failover

Changed (BREAKING)

• Change Cloudflare zone/domain name variable
• Switch to using global table for api-keys
• Switch to using global table for u2f/webauthn records

Changed (non-breaking)

• Restrict IAM permissions by AWS account, not region

Added

• Add CNAME DNS records for failover

Fixed

• Fix api_name values to match code in codeship/deploy.sh
• Use calculate API stage as serverless_stage as well