IRV actions for volumes & networks

[timalces]

At the moment in the interactive rack view, volumes & networks have the same right click options as servers. However, these devices have different possible actions than servers, and none of their actions are yet supported in the middleware.

We should determine what the appropriate/desired actions are for these device types, and update both visualiser and the middleware to carry them out accordingly.

In the meantime perhaps the status change actions should only be shown for servers.