Set things up to implement HTTP query for preaggregates

* expose a method in `NumericSerializer`
* fix `hasData()` bugs in (see https://github.com/rackerlabs/blueflood/issues/229)
* `NUMERIC` marker data type to indicate non-string + non-boolean.
* expose type of contents in `Points`.
* treat empty the same as null in `RollupType.fromString()`
log errors in `HttpRollupsQueryHandler`
reader reads from proper CF during rollup by ascertaining rollup type.
Handle the new rollup types properly on query

PlotRequestParser - Have a set of defaults for each rollup type, and a special marker set that indicates the default set should be used.
RollupHandler - Use generic `Points` instances and a utility method to compute `Points`->`Rollup`.
BasicRollupsOutputSerializer - add stats for various other fields, extract by rollup type (some extractions are invalid).
JSONBasicRollupsOutputSerializer - convert general default filter to type-specific default filter. add `toJSON()` conversion cases for the new types. make `getFilteredStatesForRollup` a moar generic.
Merge branch 'master' into aggregate_query
flatten the percentiles dictionary for timers.
add performance benchmarking tool
count needs to be set when there is a latest value.
tests for JSON serialization of new rollup types.
add K-sampling. improve reporting to only include successes, rather than in-progress requests
ninja fix for failing build.
Remove any classes that implement InternalAPI or Account.
So that we can rely on it when Things Get Tough.  We're gonna need this in a bit.
RollupType fixes

1. create a non-type for non-rollups that implement Rollup. (Go figure!)
2. Make sure that histograms are included in classOf implementation (makes it hard for SafetyTTLProvider to be safe!)
augment Rollup to supply RollupType
use ttl providers everwhere.

We currently use SafetyTTLProvider, but should switch to something supplied at runtime.
get rid of TtlCache and its ilk.
Merge pull request #237 from gdusbabek/remove_internal_api

Remove InternalAPI, TTLCache and all their miasmal friends
revert https://github.com/rackerlabs/blueflood/pull/237.
ninja fix broken build.