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.

#!/usr/bin/env python
from __future__ import print_function
import zlib, base64, sys
print(base64.encodestring(zlib.compress(sys.stdin.read())))