Support enhancements to Cisco CSR VPN REST APIs

Incorporate latest enhancements and fixes in Cisco CSR router REST API
to the VPNaaS device driver and unit test cases. Primarily, is support in
the REST API for different IKE and IPSec encryption algorithms, name length
error handling, disable of anti replay window, and IKE keep alive.

Also includes minor typos and comment fixes mentioned in previous reviews.

Note: notest_cisco_csr_rest.py, which tests the CSR REST client, is not
part of the UT suite yet, pending resolution of httmock package inclusion
as test requirement.

Change-Id: I931f487fbd4ead93a1648e89c9c383b3d55fc07c
Closes-Bug: 1303820
Switch over to FixedIntervalLoopingCall

LoopingCall has been renamed (without a change) to
FixedIntervalLoopingCall in https://review.openstack.org/#/c/26345/

Adjust to the new name so that the compatibility code can be removed.

Change-Id: I64f62dca5bee580dcd28860760208e9be8f4b659
Closes-Bug: #1307560
Merge "Support enhancements to Cisco CSR VPN REST APIs"
Notifier: Catch NotFound error from nova

If neutron sends a single event to nova and the server_uuid isn't found
in nova. The python-novaclient will raise a 404 error. This patch ensures
we explicitly catch that exception and use LOG.warning instead of LOG.exception
as this is not an error and can happen when deleting an instance if neutron
detects that the port_status goes down before the port is deleted because
nova first unplugs the vif and then deletes it from neutron.

Change-Id: I909025503fc88a92201d5247ae5223e4516e8707
Closes-bug: #1309187
netaddr<=0.7.10 raises ValueError instead of AddrFormatError

This patch ensures that ValueError is also caught in addition to
AddrFormatError as in netaddr>=0.7.11 AddrFormatError is raised and
in netaddr<=0.7.10 ValueError is raised.

Change-Id: I595c90e42129a2d365f3860e3042e826bd031365
Closes-bug: #1308675
Merge "Switch over to FixedIntervalLoopingCall"
Merge "netaddr<=0.7.10 raises ValueError instead of AddrFormatError"