build: replace verstion extraction via set to use python The version of roundup was extracted from roundup/__init__.py by sed. It is used to label the roundup.pot template file. Replaced the sed setup by importing roundup and printing the __Version__ variable. This should be less fragile to spacing and other changes.

"""
roundup.anypy - compatibility layer for any Python 2.3+
"""
VERSION = '.'.join(map(str,
                       (0,
                        3,
                        )))