Map language preselect broken (after Bootstrap upgrade?)

[hholzgra]

The map language field in the last step of the "new map" tabbed form used to get preset to the appropriate locale for the map area selected. This somehow stopped working, and lead to "None"
be the default language choice which then failed on form validation if the user did not select a different language explicitly.

This has now temporary being fixed by hard coding the default as en_US.UTF-8, but requires to be fixed fully to restore the original behavior.