Restore original ignore_module_conflict compiler option

[MrYawe]

Hi! Thanks for phoenix_storybook it's very cool.

We already set :ignore_module_conflict to false during tests to avoid these warning with gettext. This fix avoid overriding this config.

Why do you need to edit this config in the first place?

[cblavier]

Thank you @MrYawe I sincerely don't remember why I had to turn on this flag. I guess we had a warning when recompiling previously compiled story modules