Template history endpoint added. All tests passing.

Code quality fix.

app/schemas.py

@@ -1,5 +1,6 @@
 from datetime import date
 from flask_marshmallow.fields import fields
+from sqlalchemy.orm import load_only
 
 from marshmallow import (
     post_load,
@@ -93,6 +94,11 @@ class BaseTemplateSchema(BaseSchema):
 class TemplateSchema(BaseTemplateSchema):
 
     created_by = field_for(models.Template, 'created_by', required=True)
+    versions = fields.Method("template_versions", dump_only=True)
+
+    def template_versions(self, template):
+        return [x.version for x in models.Template.get_history_model().query.filter_by(
+                id=template.id).options(load_only("version"))]
 
     @validates_schema
     def validate_type(self, data):
@@ -103,6 +109,11 @@ class TemplateSchema(BaseTemplateSchema):
                 raise ValidationError('Invalid template subject', 'subject')
 
 
+class TemplateHistorySchema(BaseTemplateSchema):
+
+    created_by = field_for(models.Template, 'created_by', required=True)
+
+
 class NotificationsStatisticsSchema(BaseSchema):
     class Meta:
         model = models.NotificationStatistics
@@ -302,18 +313,6 @@ class ApiKeyHistorySchema(ma.Schema):
     created_by_id = fields.UUID()
 
 
-class TemplateHistorySchema(ma.Schema):
-    id = fields.UUID()
-    name = fields.String()
-    template_type = fields.String()
-    created_at = fields.DateTime()
-    updated_at = fields.DateTime()
-    content = fields.String()
-    service_id = fields.UUID()
-    subject = fields.String()
-    created_by_id = fields.UUID()
-
-
 class EventSchema(BaseSchema):
     class Meta:
         model = models.Event