Correct typos
Support for core Route53 HealthChecks API calls

API support for http://docs.aws.amazon.com/Route53/latest/APIReference/ActionsOnHealthChecks.html

* CreateHealthCheck
* GetHealthCheck
* ListHealthCheck
* DeleteHealthCheck
Add missing fields from DNS server requests

* HealthCheckId
* Failover
* Geolocation
Add missing fields to DNS record model

* failover
* geo_location
* health_check_id
Merge pull request #3102 from ably-forks/route-53-health-check-support

Route 53 health check support