Fix #30 -- Event microdata information (#546)

* Addition of all basics required for microdata

Microdata for event added to the head of the base event html template.

* Fixed flake8 errors & included settings checks

Fixed the flake8 too many blank line errors and changed the date and time section to refer to settings before including the time and/or the date_to.

* Typo in last commit

Fixed typo in last commit

* Fixed bracket mistake and flake8 error

Fixed tab between { and % in template tag. Removed extra lines. Removed unnecessary str() call.
Corrected binary & to [and] operator.

* Added testing for microdata

Testing added to the presale.test_event tests to cover the 4 branches and basic microdata functionality.

src/pretix/base/models/event.py

@@ -365,6 +365,26 @@ class Event(EventMixin, LoggedModel):
                 providers[pp.identifier] = pp
         return providers
 
+    @property
+    def event_microdata(self):
+        import json
+
+        eventdict = {"@context": "http://schema.org", "@type": "Event"}
+        eventdict["location"] = {"@type": "Place",
+                                 "address": str(self.location)}
+        if self.settings.show_times:
+            eventdict["startDate"] = self.date_from.isoformat()
+            if self.settings.show_date_to and self.date_to is not None:
+                eventdict["endDate"] = self.date_to.isoformat()
+        else:
+            eventdict["startDate"] = self.date_from.date().isoformat()
+            if self.settings.show_date_to and self.date_to is not None:
+                eventdict["endDate"] = self.date_to.date().isoformat()
+
+        eventdict["name"] = str(self.name)
+
+        return json.dumps(eventdict)
+
     def get_invoice_renderers(self) -> dict:
         """
         Returns a dictionary of initialized invoice renderers mapped by their identifiers.