No config-changed hook

[Marco Ceppi]

Juju get shows one configuration option for appflower:

settings:
    project:
        default: true
        description: The name of the project
        type: string
        value: appflower

However, there is no config-changed hook, nor is the project config option used in any of the hooks of the charm. The configuration option either needs to be removed or the proper hook created to allow for the config change to be executed.