Take a backup of the db and root directory at start of each fab deploy,
keeping only one previous backup.
Further tidying of fabfile.deploy function as suggested by Hamish:
- Added check_for_local_changes() (called from overriden fablib.deploy)
- Create env.project_root using existing fablib function, not manually
- Stop calling the following from fabfile.deploy because an equivalent is called from
  tasklib.deploy()
    - collect_static_files
    - update_db
    - load_fixtures
Also, added a new function for testing fabric deploys on localhost via
'fab dev deploy'.
Merge pull request #91 from jogwen/backups_for_fab_deploys

Backups for fab deploys, tidied fab deploy, and new function for testing fab deploys locally
Bump commit number of django_organizations submodule to
https://github.com/aptivate/django-organizations/commit/61ba957f131a48e9bb701336ac23702079c08049
so that we get Philip's fix to allow email addresses > 30 chars in new
organization form (fix for
https://aptivate.kanbantool.com/boards/5986-econsensus#tasks-1255113).
Also allows Organization name/slug to be up to 200 chars long (used to
be 100) and allows superusers to be able to view screens for
Organizations other than those they are member/admin/owner of (although
they can't click through to those at the moment - low priority task
https://aptivate.kanbantool.com/boards/5986-econsensus#tasks-1388735)