Allow text aggregations across the wire

[ChrisBono]

In Concierge we call SearchRequestBuilder.setAggregations(byte[]) which then causes the UTF-8 encoded byte[] representing the string form of the aggregations portion of the ES query to be passed across the wire in binary (non-human readable) format. We would like the ability to have the ES REST client have a configuration option to unroll UTF8 encoded aggregations so that in case of debugging field issues we can set this and see what in the world we are actually passing across the wire.

[vvcephei]

Is this in the slow query log or the Jetty request log (or both)?

[vvcephei]

Logged an upstream request: elastic/elasticsearch#12992