and error out on internal ones

The old name "secret_token" implied a bit that it is required for something,
but it was just an example. This new name should make it more clear.

So the bundle doesn't fail "composer install" initially.
The config is just an example, so it's not very important.

Since we inherit from all the required interfaces anyway, autoconfigure should
just work. No need to confuse users with all the special service tags.

It provides helpful methods such as denyAccessUnlessGranted() which
are likely to be needed right away, so inherit by default to make things
easier.

This adds one config entry and injects the value into a service when the bundle gets loaded.

See the README changes for how to set the config in the symfony app.

Fixes #2

The core bundle no longer requires auth by default which means all
API endpoints can be accessed without any token now.

This adds one custom controlle which requires auth as an example.

Also adds some basic tests for all the added endpoints.

And print a newline at the end