Allow Route 53 to work with zones that have health checks.
Added support for Route53 health checks
Added support for healthchecked records to zone's add_record and update_record methods
Merge branch 'route53-healtcheck' into develop, adding support for Route53 healthchecked records
    * Includes commit '0e261dcb09398e6eab1e60fefd2f4f14c9526cf9' from @xbe fork
    * Adds support for creating/deleting healthchecks