Add new features to django_cloud_browser AWS S3.

- New features:
    - Upload a file.
    - Create a new directory.
    - Delete a file or a directory.
    - Rename a file or a directory.
    - Move a file to another directory.

- Add generic methods to base.py.

- Realize generic methods for AWS under cloud/boto_base.py, and upload form
  under cloud/aws.py

- Add upload, createdir, delete, rename, move, view (some code might be still
  specific for S3, need to improve it)

- Add rename, move template files.