Add a flag in mock_data to show/hide the Hammer breadcrumb toolbar

[adamjohnson]

The ability to show/hide the hammer toolbar would be a nice addition.

Use Case

Sometimes I may be showing clients the site locally and don't want them seeing something irrelevant to the design.

Or, maybe I'm taking screenshots and don't want the toolbar in the full page screenshot.

Flag name possibilities

• show_hammer_toolbar
• hide_hammer_toolbar
• show_hammer_breadrcumbs
• hide_hammer_breadcrumbs
• ...others?

IMO we should show it by default and consider using hide_hammer_toolbar as the flag.