Support disabling body aggregation in NIOHTTP1TestServer

[simonjbeaumont]

Motivation:

NIOTestUtils provides NIOHTTP1TestServer which is useful for testing client-server interactions. Currently it uses an inbound channel handler to aggregate the entire body, which means it cannot be used to test streaming requests.

Modifications:

• Add another initializer, which takes an aggregateBody boolean parameter.
• Only add AggregateBodyHandler to the channel pipeline if aggregateBody is true.

Result:

Adopters can use NIOHTTP1TestServer to test streaming request patterns.

[Lukasa]

Love it, very good.