capacity-manila: consider "hardware_state" for capacity counting

[majewsky]

@chuan137 @Carthaca I saw from your meeting minutes that this is appearing in prod now, so I'm getting ready to start using it in Limes. Please let me know when you're done with the rollout.

Checklist:

• If this PR is about a plugin, I tested the plugin against an OpenStack cluster.
• I updated the documentation to describe the semantical or interface changes I introduced.

[Carthaca]

You are fast 👍 . Yes, I wanted to let you know, once this has been deployed everywhere (most likely Monday).

This is removing the entire pool, which means we don't just drop the capacity, but also the usage, right?
I think it would be good to keep the usage, though. That was agreed with Frank when we brainstormed about that feature. But I'm not sure what is the current agreement: I saw the issue with usable < provisioned coming up in ironic, that in theory could happen here then, as well ...

But in the end, just make CBR happy, please and have a look at consistency across the services :)

[majewsky]

CBR would like to be able to track changes to the set of pools and their hardware_state.

• add subcapacities for each pool, with capa values split according to the share-snapshot ratio
• when hardware state indicates to not count capacity, we should still include the respective subcapacity

[coveralls]

coverage: 79.56%. remained the same when pulling 335bb99 on manila-hardware-state into cff70be on master.

[Carthaca]

lgtm

hardware_state has been deployed to golden regions on Wednesday