Added genderRestriction to the recommended fields

Fix for #21

app/models/Event.json

@@ -11,7 +11,7 @@
     {"description":["While these properties are marked as optional, a data publisher must provide either a schema:startDate or specify a oa:schedule for an event."],
       "options": ["startDate","schedule"]
     }],
-  "recommendedFields": ["description","duration","organizer","eventStatus"],
+  "recommendedFields": ["description","duration","organizer","eventStatus","genderRestriction"],
   "inSpec": ["id","identifier","url","name","description","image","startDate","endDate","duration","location","organizer","contributor","maximumAttendeeCapacity","remainingAttendeeCapacity","eventStatus","subEvent","superEvent","schedule","activity","category","ageRange","genderRestriction","programme","attendeeInstructions","leader","accessibilitySupport","accessibilityInformation","isCoached","level","meetingPoint"],
   "fields": {
     "context": {