This change allows instances of ConfigObject and its children to be
converted to and from standard python types. This will allow easier
upgrade of the configuration and use of any serialization protocol (not
only pickle).

The code is not very nice (a little too verbose, I think) but it works.
Tested on a 2-node, 3-instance cluster by doing repeated conversions and
checking consistency of results.

Reviewed-by: imsnah