Added a "defNamespace" method for adding nested namespace objects to the
client.

Each namespace being created has the same capabilities for the definition
of requests/signals/slots/channels/namespaces as the client. Additionally
the namespace's path will be prepended to the method name of each
transmitted JSON rpc.
BUG FIX: Don't use the full namespace path when defining methods (for
requests, channnels etc.) inside a namespace.

The namespace's full path is only relevant for a JSON rpc's transmitted
method name. The names of methods defined within a namespace must not be
prefixed with the namespace's path.
Use the client's new namespace feature when defining the upload channel.