This fixes an installation problem where Odoo could place files in duplicate locations and fail to find required add-ons after being installed with standard Python packaging tools. The change makes installations more reliable for teams deploying Odoo in virtual environments.

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 made a dockerfile to ease reviewing and testing, it installs this Odoo branch via pip:
https://gist.github.com/bwrsandman/c9635e9164165dae86fa

This update resolves several issues affecting checkout, sales documents, and accounting workflows, including voucher validation errors and invoice generation problems. It also improves how website quote descriptions and cached website assets are handled, helping reduce errors and improve reliability for users.