Update list IAM AccessKeys

Add the creation date, including timezone info, to the data returned
when requesting all AccessKeys for an IAM user.

This fixes #75

moto/iam/models.py

@@ -177,7 +177,7 @@ class AccessKey(BaseModel):
         self.status = 'Active'
         self.create_date = datetime.strftime(
             datetime.utcnow(),
-            "%Y-%m-%d-%H-%M-%S"
+            "%Y-%m-%dT%H:%M:%SZ"
         )
 
     def get_cfn_attribute(self, attribute_name):

moto/iam/responses.py

@@ -900,6 +900,7 @@ LIST_ACCESS_KEYS_TEMPLATE = """<ListAccessKeysResponse>
             <UserName>{{ user_name }}</UserName>
             <AccessKeyId>{{ key.access_key_id }}</AccessKeyId>
             <Status>{{ key.status }}</Status>
+            <CreateDate>{{ key.create_date }}</CreateDate>
          </member>
         {% endfor %}
       </AccessKeyMetadata>