More clear way to install again QE code if the first time it fails

From user's feedback:

"Put a warning that the QE code will take some time to be installed, instead of saying that the installation wasn't successful (and e.g. suggest to refresh the page)."

I agree with this, and I now @unkcpz already put there a button to install again the codes. But in principle yeah, we can change the warning message to let the user to proceed (it seems that the button is not showing automatically the first time, when the installation gives error).