[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
```
I'm really not sure about the data stuff, always found this to be rather impredictable, and I can't experiment right now, but is it really wise to mix a change on data (which does not impact the buildout recipe) and the change of name (which does) ?