Improve support for random_trees command and similar command for adding resources

* Currently it just adds rain gardens, with minimal properties
* Update InstanceDataCommand.setup_env to use administrator role and add_default_permissions()
Make popup endpoint work for all map features

* Add MapFeature helpers
* Use _map_feature_hash instead of _plot_hash
Refactor plot detail page's template and javascript to support resources

Templates
* Create map_feature_detail.html as super-template for all map features
* plot_detail.html inherits from it
* resource.html inherits from it, but leaves details to resource-specific templates

Javascript
* mapFeature.js applies to all map features
* plot.js applies only to plots
* resource.js applies to all resources (does nothing now but will do more later)
Update URLs and views

* Convert more "plot" URLs to "feature" URLs, and "plot" views to "map_feature" views
* Make "tree detail" URL redirect to "plot detail"
* render_map_feature_detail() chooses template based on map feature type
Better unicode() method for map features