Install guide/script references igb_uio as the only usable network driver for DPDK ports

[dennisafa]

Our install guide should be adjusted to include vfio-pci and uio_pci_generic as usable kernel modules, as noted here. We should also modify our check step (locate uio) to include vfio-pci. The environment setup script should also be adjusted to use the vfio-pci kernel module, and fallback to igb_uio or uio_pci_generic in case it is not available on the system. The relevant code to change begins here.

[catherinemeadows]

Working on this now, will make a PR soon.