Created github

Please test this before you accept this PR!

This is a program equal to pastebin, which lets you get files from github and store them in your Computer. Usage is explained ingame:
Usage:
github get username/repo/branch/restOfPath 'nameOfNewFile'

You could test that with the pastebin program inside CC I uploaded to github:
https://raw.github.com/Vexatos/ComputerCraft-Programs/master/Main/utils/pastebin.lua

So you can test
github get Vexatos/ComputerCraft-Programs/master/Main/utils/pastebin.lua pastebinTest
Another spelling is possible:
github get Vexatos ComputerCraft-Programs master Main/utils/pastebin.lua pastebinTest

Then there is also the run function:
github run Vexatos/ComputerCraft-Programs/master/Main/utils/pastebin.lua 'anyMoreArguments'
github runPart Vexatos ComputerCraft-Programs master Main/utils/pastebin.lua 'anyMoreArguments'
That had to be 2 different functions because there is no specific number of Arguments per command.

Also, there is a "github help" command. Please give your opinion about this.