Fixing Server > Client rollout on initial setup

* The built-in default scenario used to mark itself as "just created"
causing it to appear "newer" than a potentially modified scenario on
the server. Fixed.
* The built-in default scenario configuration defaulted to the current
time (first start). Again, this might overwrite a potentially modified
server configuration. Fixed.
* The server used to send the list of scenarios to activate before
synchronizing available scenarios. This may cause the client to
initialize non-existing scenarios, causing a crash. Fixed.