Fixed audit notifications for dhcp-agent-network

dhcp-agent-network-add and dhcp-agent-network-remove do not
generate audit notifications which are used for security
compliance.
CRUD operations of core network resources are handled by
neutron/api/v2/base.py. In base.py, each of create(), update(),
delete() methods makes calls to oslo.messaging.Notifier.info()
to generate these notifications.
In the proposed fix, it is fixed in a similar fashion in
extensions/dhcpagentscheduler.py inside create() and delete()
methods by introducing info() method calls inside them.

Change-Id: Ia23b981b2fbe739d22ebaa7bb0975fb9e39f881b
Closes-Bug: 1317008
Remove redundant code in tests/unit/test_l3_agent

Change-Id: I87d09507cb9e9e37179d6d2035b211aa99f37260
Make test_l3_agent._prepare_router_data a module function

Remove an unneeded class variable, allowing _prepare_router_data
to be changed to a module level function. This allows the function
to be reused by other tests cases.

Change-Id: Ia4de3c535c703fbb2528e6cc9594bcd34f50aca1
Merge "Fixed audit notifications for dhcp-agent-network"
Set promote_secondaries when creating namespaces

there is a sysconf entry which controls how deletion of the primary ip
is performed (/proc/sys/net/ipv4/conf/all/promote_secondaries). when set
instead of deleting the secondary addresses, one of them will be
promoted to primary ip.

Without it, when init_l3 called on a port, it may unexpectedly delete
some useful ips.

Change-Id: I0b1b3bd6ade21129532c842daa31059ea164719e
Closes-bug: 1343320
Merge "Remove redundant code in tests/unit/test_l3_agent"
Merge "Make test_l3_agent._prepare_router_data a module function"
Merge "Set promote_secondaries when creating namespaces"