Clear __init__.py

[bartvm]

In order to make https://github.com/mila-udem/blocks-extras work as a namespace package, the __init__.py file needs to be entirely cleared (see https://pythonhosted.org/setuptools/setuptools.html#namespace-packages).

To make this work:

• Set __version__ in __init__.py instead of loading it with pkg_resources
• Move blocks.config to blocks.config.config. Not as clean, but there's not other way I can think of without programmatically changing the namespace, and I find that a bit too messy.

[rizar]

LGTM

[dwf]

Can I ask that you put some scary comments in __init__.py to discourage people from submitting pull requests that modify it?