handlers: rename obj to data for clarity
jsonpickle: add support for compiled regexes

Add a custom handler for objects returned by re.compile().

Register and lookup custom handlers by their class identifiers
rather than the actual class object itself.

This is needed because the _sre.SRE_Pattern class is not
importable in all versions of Python.  Looking it up by
name must be done instead.

Signed-off-by: David Aguilar <davvid@gmail.com>