Updates changelog header

#792 
Here is a hosted version for easy viewing: http://puu.sh/a7Vvo/ecd916c9cc.html

In addition to updating the links so they point to NTStation resources instead of /tg/station's, with Atskadan's approval I've changed the credits to list coders by contributions, so those who have committed the most get credited first.
e.g.
**NT contributors:** paprika, phil235, Iamgoofball, danno, Atskadan, GunHog, RemieRichards, Steelpoint, Donkie, VistaPOWA, Kelenius, Menshin, MrStonedOne, Jordie0608, Firecage, JStheguy, Limeliz, AnturK, StarToad, Nerolat, drynwyn, Petershmitz, Niknakflak, RandomMarine, Nnelg, Alek2ander, Nienhaus2, Boggart, Deantwo, Dorsisdwarf, Tomeno, Walter0o, YotaXP, CollenN, PinkyGatchabee, Neerti

(ordered by contributions to NTstation since it was forked from /tg/)

**/tg/ contributors:** Giacom, Ikarrus, Aranclanos, Petethegoat, Razharas, Cheridan, Incoming5643, Miauw62, Malkevin, MrPerson, hornygranny, Carn, Ergovisavi, dannno, ChuckTheSheep, Metacide, fleure, Tenebrosity, SuperSayu, Perakp, KazeEspada, AlexanderUlanH, errorage, Rolan7, kyrahabattoir, JJRcop, dumpdavidson, caelaislinn, Mloc, Tastyfish

(ordered by contributions to NTstation since the /tg/station GitHub project was created)

To explain the methodology, I split the lists so the /tg/station contributors didn't overshadow the NT ones due to the relatively short amount of time NTstation has been around to contribute to. The lists are different from one another to save space (i.e. people who have contributed to both repos are credited on the one they've contributed the highest proportion of commits to). If anyone thinks they are wrongly categorised, they can request to be moved to the other list, but this means being lower on the other list.

If you aren't listed and think you should be, please tell me.