Forbid update of HA property of routers

While the HA property is update-able, and resulting router-get
invocations suggest that the router is HA, the migration
itself fails on the agent. This is deceiving and confusing
and should be blocked until the migration itself is fixed
in a future patch.

Change-Id: I4171ab481e3943e0110bd9a300d965bbebe44871
Related-Bug: #1365426
Closes-Bug: #1378525
(cherry picked from commit 1fd7dd99ca7e5e9736200360aa354cada7fb43ff)
Add database relationship between router and ports

Add an explicit schema relationship between a router and its ports. This
change ensures referential integrity among the entities and prevents orphaned
ports.

Change-Id: I09e8a694cdff7f64a642a39b45cbd12422132806
Closes-Bug: #1378866
(cherry picked from commit 93012915a3445a8ac8a0b30b702df30febbbb728)
Add Juno release milestone

Change-Id: Iea584b00329d9474c14847db958f8743d4058525
Closes-Bug: #1378855
(cherry picked from commit 4e8a5b7de71ba6f8c050c424613c025310498940)
Remove two sets that are not referenced

The code no longer references the updated_routers and removed_routers
sets.  This should have been cleaned up before but was missed.

Closes-bug: #1232525

Change-Id: I0396e13d2f7c3789928e0c6a4c0a071b02d5ff17
(cherry picked from commit edb26bfcddf9d9a0e95955a6590d11fa7245ea2b)
Merge "Forbid update of HA property of routers" into proposed/juno
Merge "Remove two sets that are not referenced" into proposed/juno