Don't publish samples if resource_id in missing

In swift API, the user can call uri without the resource_id.
This patch skip the samples publishing instead of raising the
exception:

Traceback (most recent call last):
File "ceilometer/objectstore/swift_middleware.py", line 109, in iter_response
    bytes_sent)
File "ceilometer/objectstore/swift_middleware.py", line 160, in publish_sample
    resource_id=account.partition('AUTH_')[2],
AttributeError: 'NoneType' object has no attribute 'partition'

It print the exception of the samples publishing failure instead of
raising a exception to never break the swift API.

Fixes bug #1223259

Change-Id: I5d90fa620c8f8ea82e86524b9703049257ca0345
Avoid imposing alembic 6.0 requirement on all distros

Related-to: LP 1224666

Two of the alembic-based migrations use the new 'type_' kwarg in calls
to op.drop_constraint(), even though the old 'type' form was retained
for backward compatability:

  https://alembic.readthedocs.org/en/latest/ops.html

  "Changed in version 0.5.0: The type parameter is now named type_.
  The old name type will remain for backwards compatibility."

To avoid needlessly imposing the alembic 6.0 on distros for which this
version is not yet packaged, we revert these migrations to use the older
form.

The corresponding change to the global requirements is proposed here:

  https://review.openstack.org/48227

Change-Id: I3796ffa3de0e0f558f368d7ebf8e55c87657753d
Merge "Don't publish samples if resource_id in missing"
Merge "Avoid imposing alembic 6.0 requirement on all distros"