Fix the validation of flavor_extraspecs v2 API

"create flavor_extraspecs" v2 API does not validate the data type
of a request body. If invalid parameter is passed, an internal error
happens. If many invalid requests come, a log file would be occupied
with traceback.

In addition, it does not validate the lengths of both key and value of
extra_specs. extra_specs are stored into the instance_type_extra_specs
table, and the key and value are defined as String(255).

This patch fixes the validation code from the viewpoint of data type
and key/value length.

Closes-Bug: #1264220

Change-Id: I195bd5d45a896e9b26dd81dab1e49c9f939b4805
Reserve 10 migrations for backports

Reserve 10 migrations so that we have the option of backporting fixes
that include a db migration to the stable/icehouse branch.  We did this
same thing to allow backports to stable/grizzly in
b52a2157bedba693c5da7dcb783b7a151769d6b1 and stable/havana in
ab2c467da951071a8aac4eb6ca032371c69053ab.

The choice of 10 migrations is just a magic number.  We haven't used any
of the 10 reserved in previous stable branches, so 10 seems to be enough.

Implements blueprint backportable-db-migrations-juno

Change-Id: Ifdeba76809a705413bacee571d6d0d43ce1f062c
Ensure network interfaces are in requested order

_build_network_info_model was iterating current_neutron_ports
instead of port_ids which contains ports in their correctly requested
order. Because of this the requested nic order was no longer being
perserved. This patch fixes this and also changes the order of ports
in test_build_network_info_model() so this case is tested.

Change-Id: Ia9e71364bca6cbc24ebc1c234e6a5af14f51cd62
Closes-bug: #1300325
Merge "Ensure network interfaces are in requested order"
Merge "Reserve 10 migrations for backports"
Merge "Fix the validation of flavor_extraspecs v2 API"