Passing virial back to quantum espresso (fixes #3)

I had to change the place plugin_forces is called in espresso.
This is because in the original implementation plugin_forces
was called *before* stress calculation.
I did some qualitative test, but I am not able to run a proper
thermostated variable cell simulation with QE. Probably will
require some extra validation by QE guys.

I also updated qe version to 5.0.2