[FIX, 8.0] Package duplication with setuptools

8.0 PR of #441

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-8.0-py2.7.egg/addons
```
Remove duplicate openerp directory at root of virtualenv
```
env/openerp
```

I made a dockerfile to ease reviewing and testing, it installs this Odoo branch via pip:
https://gist.github.com/bwrsandman/c9635e9164165dae86fa