Scala Stream Collector: configure the ability to use IP address as partition key

[fblundun]

The SSC doesn't guarantee that records will be sent to Kinesis in the same order they arrive, which means sending events from the same IP to the same shard doesn't do anything.

So we should either stop using the IP address as a partition key or start guaranteeing preservation of record order.

[fblundun]

In the end we decided to make this a configurable setting, defaulting to random partitioning.

[alexanderdean]

The default will be random sharding - but if you need events sharded by ipAddress (so that users are approximately tied to one shard), you can still switch that on.

[fblundun]

I'll add an optional boolean configuration setting called collector.sink.kinesis.useIpAddressAsPartitionKey defaulting to false.