To be run via shell_plus.

NB: be sure not to run tool.save() or it will change all the backends on the tools.


>>> be = Backend.objects.get(name='nullbackend')
>>> tools = Tool.objects.all()
>>> for t in tools:
...  with open("json/%s.json" % t.name, 'w') as f:
...   t.backend = be
...   t.fs_backend = be
...   f.write(t.json())
