set and gauge serialization

Record more data with counters and gauges.  Previously I was keeping only single values.

`SetRollup`s are serialized identically to `BasicRollup`s.
`GaugeRollups`s are the same except we also include the latest time,value tuple.

Remove obviated tests from `RollupRunnableIntegrationTest`
Create proper `AbstractSerialzer`s in `NumericSerializer`.
Added utility setters to `BasicRollup`.
Needed `hashCode()`, and `equals()` implementations for `SimpleNumber` and `Points.Point`.