Added negative tests for servers

Change-Id: I6285045f023881f66e4bb42a6a188c68796ea5f5
diff --git a/storm/exceptions.py b/storm/exceptions.py
index c75544c..93ffa91 100644
--- a/storm/exceptions.py
+++ b/storm/exceptions.py
@@ -8,3 +8,11 @@
     """Exception on server build"""
     def __repr__(self):
         return "Server failed into error status"
+
+
+class BadRequest(Exception):
+    def __init__(self, message):
+        self.message = message
+
+    def __str__(self):
+        return repr(self.message)