Backport of d0653c9 LP: #1870171 - Remove the token column from the Node table.
The token column is only used by the API when allocating and machine and
listing allocated machines. When a User Token is deleted this association
causes the Node to be deleted as well. Allocated machines are already
filtered by owner and status so the token column isn't needed.
In the backport Node.token is no longer used but the column remains to
avoid creating a migration.
Backport 594f8f8bb: LP #1803188: Prevent creation of multiple IPs (per subnet, per interface) during commissioning.
In some situations, the IP address from the preboot environment differs
from the IP address acquired by the DHCP client during commissioning. This
results in MAAS linking the interface to the subnet twice, which is
unexpected and can cause problems for future usage of the machine.