Update GDK database seed to include profile images

When we generate screen shots for documentation or release blog posts, we inevitably end up with a lot of examples that look like this:

The auto-generated gravatar "identicon" sticks out like a sore thumb:

These make it harder to understand what is being illustrated in the screen shot, and it shows a general lack of polish. I think we could vastly improve this by seeding some random user profile images into our local dev environments.

We can use a pool like uifaces.com, or use the 100+ employee photos from our company team page, or pick a snarky theme like characters from Office Space.