Assigned all ArrayList.Add() to $null (#2776)
Assigned all ArrayList.Add() to $null (#2776)

* Assigned all ArrayList.Add() to $null
ArrayList.Add() returns the array list size after the add. This causes the
value to be thrown on the pipeline. Assigning them to $null as we do not
need to know the size after addition. This causes errors and unnecessary
output on the AppVeyor console.
* Changed the way nuget artifacts are added to arraylist
* Remove unnecessary `$null =` for `AddRange` call because it's a void method.

TravisEz13/PowerShell,PaulHigin/PowerShell,TravisEz13/PowerShell,JamesWTruher/PowerShell-1,daxian-dbw/PowerShell,JamesWTruher/PowerShell-1,daxian-dbw/PowerShell,daxian-dbw/PowerShell,PaulHigin/PowerShell,TravisEz13/PowerShell,JamesWTruher/PowerShell-1,TravisEz13/PowerShell,PaulHigin/PowerShell,daxian-dbw/PowerShell,JamesWTruher/PowerShell-1,PaulHigin/PowerShell