Course configuration can be modified in multiple possibly conflicting sources

[lainets]

The A+ frontend allows modification of things like module opening and closing times, but these things can also be configured from an external url. These two don't have any communication between them, so only one of them should be allowed.

For example, in Aalto the course configuration comes from mooc-grader which gets the configuration from git.

It is handy to be able to see the different settings even if the configuration comes from external sources, thus it should be enough to disable the editing while retaining the UI otherwise, in the case of using an external configuration source.