Wagalytics

Wagtail 2.9 compatibility: https://github.com/tomdyson/wagalytics/pull/53

* Complete visual overhaul
* Implements chart.js for the graph
* Adds a date range selector
* Enables exporting .ods spreadsheets containing analytics data

* Fixed 29, a bug that prevented Wagalytics 0.x from working on newer versions of Wagtail.

PyPi release: https://pypi.org/project/wagalytics/0.8.1/

Fixes 28, enabling Wagalytics to work on Wagtail>=2.1.1

Now includes per-page results.