[nailgun] Allow user to specify possible resize value for swift rings

[Vladimir Kuklin]

We need to allow user to specify resize_value for amount of swift partitions he might want to use in the future.

By default this amount should be set to 2 and result in 2048 partitions for standard HA installation.
This parameter should be sent to astute.yaml as swift['resize_value'] according to this change
https://review.openstack.org/#/c/63392

This should be done in API and UI and should be also documented to allow user to understand how much devices he can handle and what are his swift resizing constraints and why we provide such small amount for partitions in default installation (because of very slow rebalance of swift partitions for big replication factors according to https://bugs.launchpad.net/fuel/+bug/1261659).

[Mike Scherbakov (mihgen)]

Can we have support of this only in CLI?

[Mike Scherbakov (mihgen)]

I believe we can go for 4.0 without this option on UI. Vladimir - please let us know what are the current limitations of Swift usage, how many disks are supported by default.

[Vladimir Sharshov (vsharshov)]

This is feature. We can safely moved it to 8.0. Also use can do it using fuel cli.

[Alexander Kislitsky (akislitsky)]

We passed SCF in 8.0. Moving the bug to 9.0.