* use a single default configuration, share/isso.conf
* try to use config.new in some tests which are decoupled
A few tests now depend on `isso.dist` to show that they (or the used
objects) have too much dependencies and need to be rewritten.
The previous approach using a custom X-Custom header did work for the
client-side, but not for activation and deletion links. Now, you need
to add a `name = foo` option to the general section. `isso.dispatch`
then binds this configuration to /foo and can distinguish all API
calls without a special HTTP header.