fall back to superclass get_available_name
This may break on Windows, but the previous one did no check whatsoever, so this is still an improvement.
Basic readme
Merge pull request #5 from DigiACTive/docs

Basic readme
Merge pull request #2 from DigiACTive/get_available_name

fall back to superclass get_available_name
Pull upstream: Merge branch 'master' of http://github.com/wecreatepixels/django-storage-swift

Conflicts:
	README.md