Add nil check for request before calling methods

Demeter: It's the law.

This will allow the token auth object to respond with nill if the
response was never created or set to nil for some reason.

Author: csexton

lib/kracken/token_authenticator.rb

@@ -19,11 +19,15 @@ def fetch(token)
     end
 
     def body
-      JSON.parse(response.body)
+      if response
+        JSON.parse(response.body)
+      end
     end
 
     def etag
-      response.headers["etag"]
+      if response
+        response.headers["etag"]
+      end
     end
 
     private