Upgrade to OpenWayback 2.0 beta 2

This reworks the project to be OpenWayback Maven overlay.
We only keep files that have been modified.  This makes upgrades
easier: just change the version in pom.xml.  It's also the
customisation method recommended by the OpenWayback project.

Removed all checked in binaries.

Configuration has changed upstream.  Rebased on the upstream
Spring XML as recommended in the OpenWayback upgrade guide. Some
customisations may need to be reapplied.