Display unnamed devices consistently

[candlerb]

Environment

• Python version: 3.5.2
• NetBox version: 2.4.8

Steps to Reproduce

• Create an unnamed device; assign it to a rack and position
• Create another unnamed device; assign it to a rack but no position
• View these pages:
  • /dcim/devices/X/
  • /dcim/racks/Y/ (where rack Y contains the devices)

Expected Behavior

Consistent display: always show the model number in place of the missing name.

Observed Behavior

• In the device page, it displays the model number (Good)
• In the list of "Unracked devices" in the rack page, it displays the model number (Good)
• But in the rack graphical display, it displays the role rather than the model

This means you see (e.g.) "Switch" rather than "2960-X", which I think is less helpful. The role is already visible in the colour.

Workaround: you can get the model number if you hover over the item, but you can't see as much at a glance.