example site data

[dopry]

I'd really love to be able to setup the example site and got to the graphiql interface to poke around. currently there isn't any data in it. It would be nice if we had something more full featured like the bakery demo to use for the example site.

[zerolab]

we could do this 2 ways:

1. fixtures, as bakerydemo does it
2. create a scaffolding script

Note that with #289 I am aiming to re-organise things a bit in terms of repo structure, the main change being example -> tests/testapp

We used to provide some data via a bundled sqlite db, but that would get stale fairly quickly especially when testing with different Wagtail versions locally

[dopry]

I feel like fixtures would be a good approach. We're not going to be making major content changes and they're relatively easy to maintain with some caveats.