Get the correct formatPeriod off the collection.
Fix start dates following migration

The migration of dataset parameters caused an hour of timezone-ness to get added to the dates. This resulted in the first data point of the sets to return "no-data" (since I assume the monthly data is all in the database at a timestamp of midnight on the first of the month)
Test the rendering of summary time periods
Prevent stacked graphs from selecting when no model is selected

Equivalent to 3240392c769ac522dbc15eae42a71393d32e434f but for stacks as well as lines.
Fix chrome bug where border top was disappearing after sort
Add tests for stack selection on mousemove
Merge pull request #683 from alphagov/bugfix/stacked-graph-hover

Prevent stacked graphs from selecting when no model is selected
Merge pull request #681 from alphagov/bugfix/timezone-weirdness

Fix start dates following migration
Merge pull request #684 from alphagov/bugfix/sortable-tables-border

Fix chrome bug where border top was disappearing after sort
Merge pull request #680 from alphagov/bugfix/periods

Get the correct formatPeriod from the collection
Allow data source `setQueryParam` method to take hashes of attributes

Sometimes we want to set more than one property at once, without firing more than one change event. The easiest way to do this is in a single set call.
Ensure fetch of a collection completely resets the state

Retained references to selected models need to be deleted as they may no longer exist in the new collection.

Fetch needs to be called with `reset` option to ensure that old models which are no longer in the returned dataset are removed.
Use correct collection moethods instead of referencing internals

Using collections' own internal references for models is not recommended as it bypasses mutation events. By using public interface onto collections then we can ensure that events are fired, and views which are dependent on the collection contents can be updatd as appropriate.
Standardise date formats in data-source model when constructing query string

By having a single place to normalise dates we can avoid having to care about it anywhere else. We can pass dates in any valid format, and the model will magically parse them into ISO8601
Cleanup of long-winded method

This should have been done in the earlier commit/PR when it was created, but it got missed.

There's no need for the apply dance, we can just call `lastDefined` with an array, and `pluck` is way more consise.
OCD
Add basic date picker implementation
Re-render table when collection is reset

If date pickers are changed to expand/reduce the dataset, then the table should change to reflect this.
Ensure dates are always ISO8601 format

For compatability with backdrop queries, and to avoid timezone ambiguity
Clean up getPeriod methods

Most of the collection internals being referred to didn't exist. Make it a lot simpler, and draw a distinction between axis-period and period