Restructure

This restructuring is needed to provide proper python package project. Please see the diffs for changes. No functional changes should be done, only restructuring related.
Well, it will be better to have only python2 in the header and specify minimum requirement in packages and so on. This can be useful in the future, when e.g. new python2.8 will be out or something like that. It's mostly bad behavior to specify only one exact version of anything.