templates: Add an extension point to the authn plugin settings template. Allows derived templates to add something below the form fileds.

authn: Set the renderer attribute when registering settings view.

authn: Adapt and refactor plugin settings template. Adapted to the refactoring of settings views.

authn: Remove unused code Unused due to the previoud refactoring.

authn: Refactored the auth-plugins-settings base view. This allows plugins to easier extend the template context dict without duplicate the code of the base views.

pull-requests: make the catch all route also support nicer format with '-'

db: Increase __dbversion__ to 53.

db: Create database migration to rename token auth plugin ID.

authn: Add rhodecode token auth plugin to setup.py

authn: Add rhodecode token auth plugin.