Simplify static files and remove login manager

[sebschrader]

Simplify the restricted document handling introduced for #281 in #319 and remove the SipaLoginManager.

Please make sure though you did the following (tick off everything you
already did):

• Run the tests and see them pass
• Rebase your branch on top of develop
• Include tests for features you introduced / bugs you fixed

[toothstone]

I've not run the code, but self.localize_callback = gettext seems to miss compared to SipaLoginManager?

[lukasjuhrich]

If you delete things, it's good practice to run a grep through the project so one notices superfluous usages before the CI does.

tl;dr you forgot to delete the test that's associated with that module.

[lukasjuhrich]

I'm just noticing that your changes rendered the tests unusable, because they just tested the custom login manager, and not the blueprint themselves. Unfortunately, I don't have time to look into this, so you will need to fix this before I can merge.

[lukasjuhrich]

Since – judging by current observations – our user_loader exemption does not even work at the moment, we can

• rebase this branch
• implement a member_required decorator to account for ad779d1
• test the functionality

The decorator could look like this (analogous to the login_required implementation):

def member_required(func):
    @wraps(func)
    def decorated_view(*args, **kwargs):
        if request.method in EXEMPT_METHODS or current_app.config.get("LOGIN_DISABLED"):
            pass
        elif not current_user.is_authenticated \
                or current_user.is_authenticated and not current_user.is_member:
            return current_app.login_manager.unauthorized()
        return func(*args, **kwargs)

    return decorated_view