FEATURE: PCI-2479 Extend EC2 DescribeInstances API to show terminated instances
BUGFIX: get provider_location instead of host for EBS root volume at LVM
FEATURE: PCI-3773 aio=native and virtio-blk-dataplane enablement

This commit introduces following configuration options to nova.conf

* libvirt_dataplane = (True|False)
* libvirt_io_native = (True|False)

and related functionality.

All changes are backed by tests.
Merge pull request #38 from ytsarev/yut-dataplane

FEATURE: PCI-3773 aio=native and virtio-blk-dataplane enablement
Merge pull request #29 from gooddata/jpu-describe-terminated

Extend EC2 DescribeInstances API to show terminated instances for 60minutes AND get provider_location instead of host for EBS root volume at LVM
BUGFIX: PCI-3781 nova-compute service is running vgs multiple times for no reason

- refactoring part of code to get all needed values in one call instead of
  consequenti multiple call of the same expensive external command
- optimalizing calls of new methods and functions little bit
TEST: PCI-3781 update HostStateTestCase for new conditions
BUGFIX: PCI-3781 Missing pool_path variable

- adding back accidentally removed line
Merge pull request #39 from zdenekpizl/zpi-pci-3781

BUGFIX: PCI-3781 nova-compute service is running vgs multiple times