user variables to be sent in sandbox as "key=value" pairs

added user variables as key=value,
that way the argv can be loop through and find each element and define them globally. Something like follows: 

```
php run.php _POST={...} ... abc=xyz
```
In run.php
```
foreach($argv as $index => $value) {
   $elems = explode("=", $value);
   $len = strlen($elems[0]);
   switch($elems[0]) {
       case '_POST':
           $_POST = unserialize(substr($value, $len+1));
       break;
       default:
           $$key = unserialize(substr($value, $len+1));
       break;
   }
}
```
so that will create variable called $abc with value "xyz"