Restore GARP by default for floating IPs

Restore the default value of the send_arp_for_ha configuration
parameter to 3. This parameter was set to 0 by default to
prevent kernel crashes due to bug 1273386.

Change-Id: Idbdc6ff687734776ede45127878af6ad9b8b3ca1
Closes-Bug: 1317834
Add missing translation support

Update a number of files to add missing translation support.

The patch adds a new hacking check - N320. This ensures that
all log messages, except debug ones, have translations.

A '# noqa' indicates that the validation will not be done on
the specific log message. This should be used in cases where
the translations do not need to be done, for example, the log
message is logging raw data.

Change-Id: I3e1fdd04d87b09dff50950b5e85f5cacfb29afdc
Closes-bug: #1314994
Remove hard dependency on novaclient

The nova notification patch introduces a hard dependency on
novaclient when it is a runtime-configurable dependency. The
import from novaclient should be conditional on the
appropriate nova notification options being enabled in the
config.

Change-Id: I2ef4bfa4d53afc7e8c800ad8e2a8737e117af238
Closes-Bug: #1321352
Merge "Restore GARP by default for floating IPs"
Merge "Remove hard dependency on novaclient"
Merge "Add missing translation support"