Form helper changes to automatically translate the disable-with option

[Mark Edmondson]

In much the same way the submit button is automatically translated to "Create %{model}" and "Update %{model}", (where model is translated through the traditional activerecord model name translation keys) it should be possible to translate the disable-with value for specific models, with an obvious default.

Currently, the default disable-with value uses that from the button so a user sees no text change other than the button becoming disabled.

I'm proposing a change to set default translations as:

en:
  helpers:
    disable_with:
      create: Creating %{model}
      update: Updating %{model}

which can be overwritten with:

en:
  helpers:
    disable_with:
      blog/post:
        create: Creating your %{model}

And the FormHelper#submit method changing to support this.

Thoughts? Opinions?