New Features:
* NEW Store Locator feature powered by Google Maps. Use abstract `CoderedLocationIndexPage` and `CoderedLocationPage` to implement. See the documentation for more details.
* NEW import export functionality. Import or export existing pages as JSON. Import new pages from CSV files.
* Replaced Google Analytics with Google Tag Manager.
* Added additional blocks to WebPage HTML template to ease template extending.
Maintenance:
* Updated Bootstrap to 4.1.3.
* Added additional trove classifiers.
* Updated readme and documentation.