NVMe

Added a quirk to handle QEMU emulated NVMe SSDs, which report an Intel
vendor ID but don't support Intel vendor-specific log pages.

Vagrant

Modified scripts/vagrant/create_vbox.sh to run as a bash script, since
it explicitly requires bash functionality.

bdev

Fixed a bug that resulted in incorrect disk utilization reporting.

Fixed a crash when the bdev layer ran out of free bdev I/O request objects.

Fixed a race condition between closing the final bdev descriptor
and unregistering the bdev.

DPDK

Updated the DPDK submodule to be based off of DPDK 18.05.1.