This reverts commit 1ab8c19696 and
reintroduces all changes made by @dstufft.
Still, it needs more patches to reeanble the default log-to-console
behaviour. See #121.
Unfortunately zc.buildout does not support distribute/setuptools script
option (see https://bugs.launchpad.net/zc.buildout/+bug/422724), but it
does support console_scripts. This also makes the scripts importable,
allowing for unittest and code reuse.
This aids unpacking in the case of a function that isn't importable from
the worker's runtime. The unpickling will now (almost) always succeed,
and throw an ImportError later on, when the function is actually
accessed (thus imported implicitly).
The end result is a job on the failed queue, with exc_info describing
the import error, which is tremendously useful.