people.create() emails parameter should be list not string_types

The emails parameter of the people.create() method should be of type
list (and len of 1) not of type string_types.

Author: cmlccie

ciscosparkapi/api/people.py

@@ -220,7 +220,7 @@ def create(self, emails, **person_attributes):
 
         """
         # Process args
-        assert isinstance(emails, string_types) and len(emails) == 1
+        assert isinstance(emails, list) and len(emails) == 1
         post_data = {}
         post_data['emails'] = emails
         post_data.update(person_attributes)