Fix security group race condition while creating rule

Previously, it was possible for someone to create a security group rule
where the rule references another security group. To do this nova would
first create the security group rule and then look up the referenced group
(group_id's) name in order to return that via the api. During this time
it's possible for someone to delete this security group rule and the
referenced group before the call returned resulting in a 404 error being
raised. This patch addresses this issue by looking up the group name
first and then creating the security group rule in order to avoid this
from occuring.

Note: this patch also adds a test to cover the case where an invalid group
id was passed though this does not really add any real additional coverage
to the change largely because the code is currently using global stubs. That
said, the previous coverage should hopefully be sufficient

Change-Id: If58ffa5629ba5166f260379ac47922974de31be0
Related-bug: 1262566
VMware: cleanup the constructors of the compute drivers

The 'read_only' parameter was never used by the compute drivers.
The 'scheme' parameter should be passed to the base constructor.

Change-Id: I3abd40a50896664ee274f057ded8ec2460679c82
Add debug log for core_filter

Sometimes operator need information why the host doesn't pass
the check of scheduler, this patch adds information for core
filter if virtual cpu is not enough on the host.

Change-Id: Ie05d9184435a4fc4cff1af26812c01a3cc226fff
Partial-Bug: #1301830
libvirt: add support for memory tuning in config

Add a libvirt config class for dealing with the XML elements
under the <memtune> element of the guest schema

Blueprint: virt-driver-large-pages
Change-Id: I141fcf4fd95f61f7fc3a5d0209dc2b1319ede941
Updated from global requirements

Change-Id: Ide162a1145a2c8b67546812fbfcdc24a5753818b
Merge "libvirt: add support for memory tuning in config"
Merge "VMware: cleanup the constructors of the compute drivers"
Merge "Updated from global requirements"
Merge "Fix security group race condition while creating rule"
Merge "Add debug log for core_filter"