Match All scsi controllers instead of just LSI controllers

When adding extra disks to a vm, the code finds storage controllers that match a specific LSI controller.  The code has been updated to check if the object is an instance of a class that extends VirtualSCSIController so will now find any scsi controllers supported by RBVMOMI.

There is also an edge case where the device is lost if any of it's disks are found before the device itself in vm.config.hardware.device.  In that case, the device would never be added to scsi_tree.