Support basic Wekan permissions

It came to light that currently all users that have access to Wekan get full admin access, regardless of their Stackspin role (admin/user) stackspin#1597 (closed). To fix that, we need some Wekan-specific support in the consent handler to add group information to the userinfo token based on Stackspin roles.

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information