[FIX] Package duplication with setuptools

Fix #185
Fix addons not found error with odoo.py after setup.py
Include addons in virtualenv site-packages egg directory
```
env/lib/python2.7/site-packages/openerp-8.0alpha1-py2.7.egg/addons
```
Remove duplicate openerp directory at root of virtualenv
```
env/openerp
```
@bwrsandman I understand, and have of course nothing against it. I've filled an issue on the recipe to track the fact that it'll need to adapt : https://bugs.launchpad.net/anybox.recipe.openerp/+bug/1332147, which is fortunately not really hard but will require a new release

In the meanwhile, could you keep these two concerns separate ? I'd understand also if you'd lack the patience to make many PRs for the setup stuff.

Cheers,