Provide RESTful equivalent of YarnClientImpl

For YARN clients to make effective use of this, we need an equivalent service YarnClientImpl. The closer the REST client to this existing class (and the YarnClient API, the easier the migration.

Requirements of SLIDER-170

Needs

• work long-haul, through proxies and security gateways like Apache Knox
• Integration with Hadoop security
• diagnostics and meaningful error messages
• ability interrupt outstanding calls

Wants

• ideally some performance metrics to track long-haul perf issues (prefer codahale to Hadoop, for embeddability)
• tunable restart/retry policy