Improve allowed values support

Even though I think it's a bit wonky to put allowed values for user-generated other option it is still a possibility. I know that it "works" right now, but it's not pretty. There's an issue with default value that has to be worked around.

To start with I'm going to write a patch to just test the allowed values. And then use this task to make more improvements to this.

Current patch completes all tests showing that you can use allowed values.