made ps display the pid correctly

exec/ps.lua

@@ -1,5 +1,5 @@
 print("PID# Parent | Name")
 for k,v in pairs(os.tasks()) do
  local t = os.taskInfo(v)
- print(string.format("%4d   %4d | %s",k,t.parent,t.name))
+ print(string.format("%4d   %4d | %s",v,t.parent,t.name))
 end