Remove webchat as a built in command.

Webchat will now be an extension that can be installed.
the extension is here:
https://github.com/hemna/aprsd-webchat-extension

Install it from git or pypi.

tests/cmds/test_send_message.py

@@ -27,8 +27,8 @@ class TestSendMessageCommand(unittest.TestCase):
         if password:
             CONF.aprs_network.password = password
 
-        CONF.admin.user = "admin"
-        CONF.admin.password = "password"
+        # CONF.aprsd_admin_extension.user = "admin"
+        # CONF.aprsd_admin_extension.password = "password"
 
     @mock.patch("aprsd.log.log.setup_logging")
     def test_no_tocallsign(self, mock_logging):