Fixing message in config manager (#302)

Author: aliabbasrizvi

core-httpclient-impl/src/main/java/com/optimizely/ab/config/HttpProjectConfigManager.java

@@ -94,7 +94,7 @@ public String getDatafileFromResponse(HttpResponse response) throws NullPointerE
             }
             return EntityUtils.toString(entity, "UTF-8");
         } else {
-            throw new ClientProtocolException("unexpected response from event endpoint, status: " + status);
+            throw new ClientProtocolException("unexpected response when trying to fetch datafile, status: " + status);
         }
     }