Allow setting of locale aliases in project language settings.

 - make the mapping textbox show and hide
 - limit input to 255 characters to match the database field
 - allow aliases to be set for two different languages without error

Setting aliases for different locales on the same pageload causes a null pointer
exception when looking up the versions - seems very unrelated so presumably some
silent error related to having multiple fields using the same property in the
backing bean.