Fix extras_require and environment markers in sdist

Currently, environment markers in extras_require (e.g. {':python_version=="2.6"': ['unittest2']}) in sdist do not work.
The plan is to use pkg_resources.Distribution which will give it for free.

First commit is to make sure we do not put editable_options in extras (parse_editable return types are currently merging the two).
I don't think we need this here, at the very least it should be ``logger.debug`` not ``logger.info``.