Move confirm email settings processing to func.
Add signal receiver reseting CONFIRM_EMAIL...

Create update_confirm_email function that resets settings related to
email confirmation.
Connect it to setting_changed signal.
It's needed in tests for override_settings to work.
Add override_settings for existing tests

Some of existing tests depend on confirm email settings being set to
default values. Since in test_settings those setting are not present
default values are used and travis tests pass, but if developer would
run tests in his/hers project with non-default values of settings tests
would fail. So added override_settings to make sure each test is run
with proper settings.
Add testing of action_done in template context

Subclasses of ActionRequestView now should pass additional variable
action_done to template context. This variable should be false if email
confirmation is on because actions can not be done in
<Action>RequestView.
Add tests for requests without email confirm.

Add test_<action>_request_post_no_email methods testing:
* response status
* context variables
* db changes
* mail outbox
for subscribe, unsubscribe and update requests with email confirmation
switched off.
Merge pull request #1 from jkuczm/confirmation_email

Add tests for bypassing email confirmation