Hierarchial Data Builder

- Added hierarchialData attribute to VisType
- Created buildHierarchialData() method
- Moved pie tooltipFormatter to _hierarchial_tooltip_formatter.js
- Added initial testing structure for buildHierarchialData()
- Added tests
- Closes #1682
Fixing the raw data to do sensible things.
For the Kibana metrics will always be numbers so we want the column to
always align right.
Adding more tests and features for filter bar

- Add support for _previuos to _array_to_linked_list
- Add support for parent to _transform_aggregation
- Add tests for _array_to_linked_list
- Add test for setting the parent of the element for hierarchial data
Fixing the tooltip so it correctly walks up the branch
[hierarchical data] attach the metric vis at all levels of the request
Not setting the value correctly when the agg value is zero
[agg_types/terms] assume sub-metric with a hierarchical vis
[aggConfigs/toDsl] don't add subaggs unless needed
Merge pull request #1684 from simianhacker/hierarchial-data

Hierarchal Data Builder