Move non-trivial code from namespace __init__.py

• Move non-trivial code from slapos/recipe/__init__.py to slapos/recipe/utils.py.

This is needed for buildout 3 because buildout now uses pip and pip drops __init__.py in namespace packages.

New-style namespace packages are packages that do not contain an __init__.py. The native Python import mechanism now handles such packages as namespaces.

Legacy namespace packages predate this feature and achieve the same behavior with an __init__.py that uses a legacy namespace mechanism such as:

__import__('pkg_resources').declare_namespace(__name__)

Pip just drops such legacy __init__.py in packages declared as namespace packages. To work around this buildout 3 creates a new __init__.py using the above legacy namespace implementation.

• slapos.recipe.cmmi and rubygemsrecipe will need to adapt to the changed path.