replace Merry Christmas for italian

as for issue #634
Merge pull request #652 from endelwar/master

replace Merry Christmas for italian
Translate Happy Holidays to Norwegian
Happy Holidays in Pt
Merge pull request #653 from arthurnn/pt_br_happyholidays

Happy Holidays in Pt
Add happy holidays in French
Merge pull request #654 from toch/happy-holidays-in-fr

Add happy holidays in French
Merge pull request #655 from kimroen/translate-happy-holidays-norwegian

Translate Happy Holidays to Norwegian
Added initial contributor code of conduct

Using v1.0 of http://contributor-covenant.org/
Added contact email address
Merge pull request #656 from 24pullrequests/coc

Added initial contributor code of conduct