WIP [NX-525] shared database support

https://issues.sonatype.org/browse/NX-525

also addresses:
https://issues.sonatype.org/browse/NEXUS-6698
https://issues.sonatype.org/browse/NEXUS-6619
maybe?  haven't actually tested if this works asis or not, but I'm thinking its probably not working?

`dir.toURI().getPath()` might be sufficient?