PermissionsRequiredMixin: Add helper functions for overiding
Subclass PermissionRequiredMixin in MultiPermsRequiredMixin

Allows for better code re-use and overriding of default behavior.
Update docstrings and comments for clarity.
Update doc string
Merge branch 'master' into pr/67
AuthorizedRedirectMixin

View mixin which redirects to a specified URL if authenticated. Can be
useful if you wanted to prevent authenticated users from accessing
signup pages etc.
Added tests for AnonymousUserOnlyMixin (previously AuthorizedRedirectMixin).
Cleanup of renaming for AnonymousUserOnlyView
Renamed to AnonymousRequiredMixin, added reverse lazy test, fixed typos and now using LOGIN_REDIRECT_URL
Make it possible to use CanonicalSlugDetailMixin with custom url kwargs
added universal wheel support
Add an ExtraContextMixin
Fixed a typo.
AllVerbsMixin: call a method for all HTTP verbs

The dispatch method will extra the attribute specified by the
class attribute "all_handler", the default value of which is "all".
The dispatch method then calls this method, without checking what
the HTTP verb is. If "all_handler" is not specified (techincally
if it evaluates to False) then ImproperlyConfigured exception is
raised.

Tests are in tests/test_other_mixins.py::TestAllVerbsMixin.
Fixed GroupRequiredMixin.check_membership

Previously, if get_group_required would return a string, the checker would work fine (see if the group string was inside user.groups). If get_group_required returns a sequence, you would be comparing whether the entire sequence (of possible groups) appears as an entry in user.groups.

Now, check_membership checks whether any of the groups in self.group_required appears in user.groups (as intended, see https://github.com/brack3t/django-braces/issues/35).
Fixed the tests (that prevented detection of the check_membership).

test_with_group_list
Previously, the test modified a group_required property from a GroupRequiredView **instance**, but not from the **class**. When the client is launched to perform a request it instantiates a **new** instance, with the original class variable 'test_groups' and not the intended sequence.
Now the test modified the class variable, so the client can create an instance with the correct attribute. (value is restored before finishing the test).

test_with_unicode
Similar bug with the instance variable vs class variable, which went undetected because of another bug when modifying the group name. When calling user.groups.all()[0] an object is returned (and then modified), but since its reference is not saved, the changes are lost (rerunning user.groups.all()[0] returns the instance saved in the DB, and not the modified one). That bug prevented the user group from being modified, so the test deceptively passed.
Merge pull request #103 from ykalchevskiy/patch-1

Fixed a typo.
Merge pull request #104 from prasanthn/allverbsmixin

AllVerbsMixin: call a method for all HTTP verbs
If superuser, skip group check. Superuser has all perms and thus all groups.
PEP8 fixes.