updates demo/requirements
fixes minor typos in docs
Merge branch 'develop' of github.com:saxix/django-concurrency into develop

* 'develop' of github.com:saxix/django-concurrency:
  [requires.io] dependency update
add python 3.3
updates requirements of demoproject
updates docs
backward compatibility updates. Do not check for concurrency if `0` is passed as version value
    (ie. no value provided by the form)
bump 0.7.1
Merge branch 'heads/0.7' into develop

* heads/0.7:
  bump 0.7.1
  backward compatibility updates. Do not check for concurrency if `0` is passed as version value     (ie. no value provided by the form)

Conflicts:
	CHANGES
	concurrency/__init__.py