Catching up Vim with all the latest TextMate/Sublime themes

Created Vim versions of the following themes:

 - BoxUK
 - Darkside
 - Github
 - Gloom
 - Glowfish
 - LastNight
 - NaturalContrast
 - Tron
 - TronLegacy

Some don't quite seem 100% perfect (LastNight for instance) but it's better than nothing!

This hopefully satisfies concerns noted in #15.