InstallAuth was in the installer directory, which meant that Plack was
unable to find it, and so running the webinstaller would fail. This
moves it into C4,
Test plan:
* Make sure the web installer runs under plack
* Make sure the web installer runs under non-plack
Signed-off-by: Brendan Gallagher <brendan@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>
Robin Sheat