Commands with kwargs fail with TypeError instead of ConnectionError when connection is down

When the connection to Redis server is down, ConnectionHandler replaces proper methods with dummy `lambda`s which accept only positional arguments. If some Redis command is then called with keyword arguments, a confusing traceback is produced:

    2013-03-30 23:33:05+0400 [HTTPChannel,1,127.0.0.1] Unhandled Error
    Traceback (most recent call last):
      File "/usr/local/lib/python2.7/dist-packages/twisted/protocols/basic.py", line 581, in dataReceived
        why = self.lineReceived(line)
      File "/usr/local/lib/python2.7/dist-packages/twisted/web/http.py", line 1611, in lineReceived
        self.allContentReceived()
      File "/usr/local/lib/python2.7/dist-packages/twisted/web/http.py", line 1686, in allContentReceived
        req.requestReceived(command, path, version)
      File "/usr/local/lib/python2.7/dist-packages/twisted/web/http.py", line 790, in requestReceived
        self.process()
    --- <exception caught here> ---
      File "/usr/local/lib/python2.7/dist-packages/twisted/web/server.py", line 192, in process
        self.render(resrc)
      File "/usr/local/lib/python2.7/dist-packages/twisted/web/server.py", line 241, in render
        body = resrc.render(self)
      File "/usr/local/lib/python2.7/dist-packages/twisted/web/resource.py", line 250, in render
        return m(request)
      File "twistedweb_server.py", line 59, in render_GET
        self.db.zrangebyscore('foo', count=33, offset=0)
    exceptions.TypeError: <lambda>() got an unexpected keyword argument 'count'

Attached patch allows this dummy `lambda` to accept keyword arguments, so that a proper error message can be seen in server log:

    2013-03-30 23:32:08+0400 [HTTPChannel,1,127.0.0.1] Unhandled Error
    Traceback (most recent call last):
    Failure: txredisapi.ConnectionError: Not connected