Timeseries graphs with Rickshaw.

I've extracted graphs to their own partials, which seems sane.
Timeseries graphs can be defined as graph types.
Timeseries queries are based on date aggregations (by the minute,
at the moment).
Merge branch 'time_series_graph'
Reflecting new CDN path.
You should be able to re-order a field you've just created.
Refactoring all these lists of methods into single methods on respective objects. Tidier.
Linear interpolation of time-series graph is less horrible.
Oops, forgot to update edit graph page.
Collector: field type json is shared
Field types: now picked up from archetype in field_types.json