Automatic merge from submit-queue
Dynamic provisioning for flocker volume plugin
Refactor flocker volume plugin
* [x] Support provisioning beta (#29006)
* [x] Support deletion
* [x] Use bind mounts instead of /flocker in containers
* [x] support ownership management or SELinux relabeling.
* [x] adds volume specification via datasetUUID (this is guranted to be unique)
I based my refactor work to replicate pretty much GCE-PD behaviour
**Related issues**: #29006#26908
@jsafrane @mattbates @wallrj @wallnerryan
We had another bug where we confused the hostname with the NodeName.
To avoid this happening again, and to make the code more
self-documenting, we use types.NodeName (a typedef alias for string)
whenever we are referring to the Node.Name.
A tedious but mechanical commit therefore, to change all uses of the
node name to use types.NodeName
Also clean up some of the (many) places where the NodeName is referred
to as a hostname (not true on AWS), or an instanceID (not true on GCE),
etc.
* flocker datasets should be attached using an unique identifier. This
is not the case for the name metadata used by datasetName
* allow only one of datasetUUID / datasetName specified
