Moving away from bootstrap-buildout.py

As you may have already noticed, setuptools is deprecating ez_setup.py, the module that allowed setuptools to install itself. With that, it has become evident that zc.buildout will no longer be able to self-bootstrap and, at a certain point, it will be removed. So far, a hack is put in place pinning the version of setuptools to 33.0.0 (it is now on 34.3.1 already...), which is the last to provide this functionality. See:

• https://github.com/buildout/buildout/issues/289
• https://github.com/pypa/setuptools/issues/581

The message printed out is:

$ python bootstrap-buildout.py
ez_setup.py is deprecated and when using it setuptools will be pinned to 33.1.1 since it's the last version that supports setuptools self upgrade/installation, check https://github.com/pypa/setuptools/issues/581 for more info; use pip to install setuptools
Downloading https://pypi.io/packages/source/s/setuptools/setuptools-33.1.1.zip
...

I propose:

1. we start shipping zc.buildout as part of our bob-devel environment and as a bob dependence
2. we remove bootstrap-buildout.py from all packages
3. after activating the conda environment, the user does only buildout (instead of ./bin/buildout)
4. update instructions on bob.extension's guide to reflect these changes.

I tested the above changes and that seems to work fine. Are there any objections?

ping @bob