Remove unnecessary verbosity in step naming/creation

I'm of the opinion that having stuff like `createSupplierAuctionItemInfoEditStep` is basically way too long and should not be the encouraged default.
A great example of where this become relevant is in accessing the view from the parent pane
```
this.listenTo(this.supplierAuctionItemInfoEditStep, function(){})
```
VS
```
this.listenTo(this.step, function(){})
```

Since we only have one step in a pane, it seems superfluous to give this one view that each pane will require a specific name, instead of defaulting to something more predictable.