Sync with django-storages or provide installation instructions

[wimleers]

django-storages has had quite an overhaul over the last few months. We should update the code that's included with File Conveyor to the latest of django-storages. Alternatively, we should no longer include that in File Conveyor, but add installation instructions to install django-storages. After all, django-storages has been updated to work with easy_install, so installation should no longer be an issue.

[benoitbryon]

Additional notes...

The layout of django-storages included in fileconveyors looks like the one at http://code.welldev.org/django-storages/src/b1bd0ff0ce55, which is just before version 1.0. Versions 1.0 and above of django-storages are available on Pypi.

The dependency could be managed as proposed in #86 for Django, Python-cloudfiles and Boto. But here, some internals of Fileconveyor (at least transporters) have to be updated too.