Changes in export_database script.

- Many bugfixes.
- Added lots of documentation.
- Fixed plenty of pep8 errors.
- Reset container name to DPLA.
    - Left the 'test' container for tests, however commented out.
    - Added comments to the production and test container.
- Fixed a view in export_database.js.
    - The view in export_database.js for listing all source names didn't
      work as there were missing view _id.
- Fixed a bug with running script when cloudfiles are not installed.
- Removed basic authentication header function.
- Refactored export_database.
    - Added action dispatcher.
- Modfied export_database.
    - It now uses env variables for Rackspace access.
    - Removed username/password for couchdb - now everything is in db url.
    - Fixed a bug when script is run without params.