L3 Agent restart causes network outage

When a L3 agent controlling multiple qrouter namespaces
restarts, it destroys all qrouter namespaces even if
some of them are still in use.  As a result, network
traffic could be stopped on the VMs that use the
networks associated with these namespaces.

So what is needed is for the L3 agent to preserve those
qrouter namespaces a L3 agent instance recognizes and to
destroy those it does not know about.

Closes-Bug: #1175695

Change-Id: Idae77886bd195d773878c3d212ccfd56269216fb
(cherry picked from commit 011d99f300ea5d5f4ce48023bd04a795a4872287)

Backported-from: icehouse
Closes-rally-bug: DE833
Upstream-Review: https://review.openstack.org/#/c/84420/
Merge pull request #32 from CiscoSystems/de833

L3 Agent restart causes network outage
DE734: Instance not getting DHCP due to missing of vlan tag on openvswitch port

- Initial refactoring of a patch authored by AT&T
- Moved get_port_tag_dict to ovs_lib.py which seemed more appropriate.
- Now only examining a port to look for a tag on specific types of tenant networks.
- Added tenant_network_type to the initialization of OVSNeutronAgent
- Now checking for specific tenant network types before looking for vlan tags.
- Now setting self.tenant_network_type from the OVS config.
- Adjusted unit test.
- Adjusted log message when port in forced to resync.
- Clean up test values.
- Removed incorrect spacing.

Closes-rally-bug: DE734
Not-in-upstream: true
Revert "DE734: Instance not getting DHCP due to missing of vlan tag on openvswitch port"
Merge pull request #39 from CiscoSystems/revert-35-de734

Revert "DE734: Instance not getting DHCP due to missing of vlan tag on o...
Merge remote-tracking branch 'origin/cis-havana-staging' into merge-cis-havana-staging
Merge pull request #45 from retr0h/merge-cis-havana-staging

Merge cis havana staging