Getting more than one GPU is not intuitive

[rizar]

I had to pass both -g 2 and -G 2.

[mgermain]

Usually, you only need -g2 that says that each of your commands will need 2 GPUs.

If you need to specify -G2 it's probably because you are trying to run on a queue that has only one GPU like gpu_1 and that you need to override the defaults of the queue.

The error thrown is probably not clear and it could be handled more gracefully.

[mgermain]

Created issue #155 to solve this.