Repository: Shopify/shopify_python_api

Issue:
TypeError: not all arguments converted during string formatting in /resources/events.py
Getting the following error trying query order events
```
>>> import shopify
>>> shopify.Order.find(2098647662664).events()
Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/usr/local/lib/python3.6/site-packages/shopify/mixins.py", line 36, in events
    return shopify.resources.Event.find(resource=self.__class__.plural, resource_id=self.id)
  File "/usr/local/lib/python3.6/site-packages/pyactiveresource/activeresource.py", line 385, in find
    return cls._find_every(from_=from_, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/pyactiveresource/activeresource.py", line 522, in _find_every
    path = cls._collection_path(prefix_options, query_options)
  File "/usr/local/lib/python3.6/site-packages/pyactiveresource/activeresource.py", line 613, in _collection_path
    'prefix': cls._prefix(prefix_options),
  File "/usr/local/lib/python3.6/site-packages/shopify/resources/event.py", line 10, in _prefix
    return "%s/s/%s" % (cls.site, resource, options["resource_id"])
TypeError: not all arguments converted during string formatting
```
there appears to a missing percent sign for the string formatter:
https://github.com/Shopify/shopify_python_api/blob/master/shopify/resources/event.py#L10

Discussion:

Patch:
diff --git a/shopify/resources/event.py b/shopify/resources/event.py
index 5d266d0..0fc1e6f 100644
--- a/shopify/resources/event.py
+++ b/shopify/resources/event.py
@@ -7,6 +7,6 @@ class Event(ShopifyResource):
     def _prefix(cls, options={}):
         resource = options.get("resource")
         if resource:
-            return "%s/s/%s" % (cls.site, resource, options["resource_id"])
+            return "%s/%s/%s" % (cls.site, resource, options["resource_id"])
         else:
             return cls.site


Test patch:
diff --git a/test/event_test.py b/test/event_test.py
new file mode 100644
index 0000000..67e8033
--- /dev/null
+++ b/test/event_test.py
@@ -0,0 +1,12 @@
+import shopify
+from test.test_helper import TestCase
+
+class EventTest(TestCase):
+    def test_prefix_uses_resource(self):
+        prefix = shopify.Event._prefix(options={'resource': "orders", "resource_id": 42})
+        self.assertEqual("https://this-is-my-test-show.myshopify.com/admin/api/unstable/orders/42", prefix)
+
+    def test_prefix_doesnt_need_resource(self):
+        prefix = shopify.Event._prefix()
+        self.assertEqual("https://this-is-my-test-show.myshopify.com/admin/api/unstable", prefix)
+