Let's mash Spring's RestTemplate and Netflix's Hystrix together!

This is a RestTemplate sublass that uses Hystrix underneath to execute requests as Hystrix commands. The goal is to:

• Provide a RestTemplate drop-in replacement that leverages Hystrix for fault-tolerance and latency
• Provide another RestTemplate subclass that exposes more of the Hystrix API and functionality while maintaining a Spring-y feel

• HystrixRestTemplate, with the DefaultResponseErrorHandler, will count any HTTP responses with 400 or 500 series status codes as Hystrix command execution failures. If a 400 or 500 series status code response should NOT be counted as a failure, implement a custom ResponseErrorHandler to either wrap the HttpStatusCodeException in a com.netflix.hystrix.exception.HystrixBadRequestException or not throw at all.
• Take care in configuring the underling org.springframework.http.client.ClientHttpRequestFactory's timeouts and retries as these should be configured with consideration to Hystrix's command timeout configuration.