scanner: allow local Debian Maven repo file:///usr/share/maven-repo
scanner: allow local Debian Maven repo file:///usr/share/maven-repo

It is now possible to build an app using only things in Debian.  Since the
buildserver will always control the contents of file:///usr/share/maven-repo,
it is the most safe repo there is.

fdroidtravis/fdroidserver,f-droid/fdroidserver,f-droid/fdroidserver,f-droid/fdroidserver,fdroidtravis/fdroidserver,fdroidtravis/fdroidserver,f-droid/fdroid-server,f-droid/fdroidserver,fdroidtravis/fdroidserver,f-droid/fdroidserver,f-droid/fdroid-server,f-droid/fdroid-server,f-droid/fdroid-server,f-droid/fdroid-server