Do not allow event names with hyphens in them

Fixes #36

socketio/server.py

@@ -138,6 +138,8 @@ class Server(object):
         client's acknowledgement callback function if it exists. The
         ``'disconnect'`` handler does not take a second argument.
         """
+        if '-' in event:
+            raise ValueError('event names cannot contain hypens')
         namespace = namespace or '/'
 
         def set_handler(handler):

tests/test_server.py

@@ -45,6 +45,10 @@ class TestServer(unittest.TestCase):
         self.assertEqual(s.handlers['/']['disconnect'], bar)
         self.assertEqual(s.handlers['/foo']['disconnect'], bar)
 
+    def test_on_bad_event_name(self, eio):
+        s = server.Server()
+        self.assertRaises(ValueError, s.on, 'two-words')
+
     def test_emit(self, eio):
         mgr = mock.MagicMock()
         s = server.Server(client_manager=mgr)