[#636] Fix deleted members having rights
[#636] Check we set state to active
[#636] Fix group auth tests.

A partial update was removing members
from a group so at the next call to group_update
authorization was denied. The whole group dict
is now fetched using group_show before being
updated.

Also some PEP8 fixes.
Merge remote-tracking branch 'origin/master' into 636-auth-bug
Merge pull request #636 from okfn/636-auth-bug

Access is not restricted when user is removed from Group