incremental improvements to VM Commission workflow

Commission workflows are due for a refactor, but in the meantime, this is a bit better.

* Renamed the ambiguous 'App.CommissionVmSpecs' class object to 'App.CommissionVmHostSpecs' to express that it is a spec object for a single virtual host.
* Route states rationalized for the template state ('commissionVm') and the commission specs state ('commissionVmSpecs'). Entering either via URL is now consistent, although the model hook for 'commissionVmSpecs' returns a literal empty array, which the template interprets as an error, and presents in turn a friendly message.