Add flag days and missing holidays norway

[havardnyboe]

Added flag days and other missing holidays and international days.

New additions are:

• All official flag days
• Valentines, International Women's Day, and April Fools
• Other minor holidays like Allehelgensaften, and Askeonsdag

Corrections: Name of 17. may changed from "17. mai" to "Grunnlovsdagen", to name it like it is named as a flag day.

[commenthol]

@havardnyboe Thanks