serialize sets the same way as basic rollups.
serialize more things in gauges.

Basically, they are a basic rollup + last value.

This required a teeny change in the way BasicRollups are deserialized: we only deserialize 4 stats now, rather than everything until the stream empties.
Fix counter and gauge serialization bugs

* adjust `RollupRunnable` test to build preag metrics from single values (not rollups).
* and store them correctly.
* choose the right serializer for full-res data in `AR.getDataToRoll()`.
* add some comments about some refactoring I'd like to see.
* Adjust counter to handle all number types, not just longs (promote to double whenever encountered)
* Add raw computes for counter and gauges.
Merge branch 'master' into counter_gauge_serialization

Conflicts:
	blueflood-core/src/integration-test/java/com/rackspacecloud/blueflood/service/RollupRunnableIntegrationTest.java
Use `Number` throughout `SimpleNumber`.
expose `getLatestNumericValue()` as a convenience function in `GaugeRollup`.
have `getLatestValue()` return a `SimpleNumber`.
Merge pull request #158 from gdusbabek/counter_gauge_serialization

set and gauge serialization