Since there is no demo or us site anymore we can simplify the structure
somewhat by moving the sandbox one directory up

A gremlin spawned in 860fab7ba7. This was
bringing down the sandbox site.

Most email servers don't respect capitalisation, and many users don't
know about it. So Oscar now does what the rest of the world does, and
ignores the capitalisation when looking up an email address.

Fixes #1179.

Example sites now sit in their own folder (sites) for easier
organisation.

This allows members of the public to play around with the dashboard
site.