Deprecate nova-manage flavor subcommand

The nova client already has the following flavor commands:

flavor-access-add    Add flavor access for the given tenant.
flavor-access-list   Print access information about the given flavor.
flavor-access-remove Remove flavor access for the given tenant.
flavor-create        Create a new flavor
flavor-delete        Delete a specific flavor
flavor-key           Set or unset extra_spec for a flavor.
flavor-list          Print a list of available 'flavors' (sizes of
flavor-show          Show details about the given flavor.

This covers what nova-manage flavor was providing so let's deprecate the
legacy nova-manage subcommand and mark it for removal in the K release.

There is not a bug or blueprint for this. The flavor subcommand is
completely duplicated in nova client. It is accessing the database
directly and we want to move to using flavor objects which would go
through conductor. So this could be considered part of the objects
conversion for flavors.

For some other commands like service, db and host it makes sense to
leave those so you can access the database before the api service is
running, but that's not the case for flavors.

UpgradeImpact: nova-manage flavor command is deprecated, use nova client

Change-Id: I8709bc9af4e490142e44c6dc61fd0aaa3a392b68
replace NovaException with VirtualInterfaceCreate when neutron fails

Currently NovaException is being raised by the _neutron_failed_callback()
and being treated in a try..except block that wraps the _crate_domain method.
The exception is too generic and will catch any exceptions, which are
subclasses of NovaException (for example: ObjectActionError),
making the domain variable not be defined and will mask the original exception.

Suggesting to raise and catch the VirtualInterfaceCreateException and
treat the domain destroy and cleanup with save_and_reraise_exception
in the except block.

Change-Id: Ic972e286ded4e8b9d79ce1b0aa514bb4623d5f0b
Remove a bogus and unnecessary docstring

A docstring in the Cinder API check_attached method was wrong, and is
quite unnecessary as well since the method is pretty much self
explanatory.

Change-Id: I179611bc627d49a4ffaa58f27dd1b7dcb33c6870
Merge "Deprecate nova-manage flavor subcommand"
Merge "Remove a bogus and unnecessary docstring"
Merge "replace NovaException with VirtualInterfaceCreate when neutron fails"