Store volume backed snapshot in current tenant.

Fix owner of a creating volume backed snapshot.

Snapshot of an instance booted on a volume based on another tenant's
public image is created in the wrong tenant when invoked by admin.

Snapshot metadata (including owner) is based on image metadata. But
when the snapshot is being created by admin, Glance doesn't change
it's owner if it's set. So we forcibly remove owner (tenant)
attribute from image metadata.

Change-Id: I662dfa4f81e24cb2553ffa2578f4c8530eee9fd3
Closes-Bug: #1322195
Raise specific error of network IP allocation

Currently Nova raise "Neutron error: quota exceeded" when
neutron client state code is 409 in IP allocation without
caring about if the real error is over quota.

This fixes raises PortLimitExceeded if error from neutron
client is OverQuota and raises NoMoreFixedIps if error from
neutron client is IpAddressGenerationFailure. If the error
is neither of these two errors above, it reraises the original
exception from neutron client.

Change-Id: I0d1942587a359acccfca5298c2dcb4b21d971a42
Closes-Bug: 1331353
Merge "Raise specific error of network IP allocation"
Merge "Store volume backed snapshot in current tenant."