REIVEW: [NX-518] Orient database manager

This PR addresses the following issues:

https://issues.sonatype.org/browse/NX-518
https://issues.sonatype.org/browse/NX-519
https://issues.sonatype.org/browse/NX-542
FTR I think once we get a bit further along with this api we'll circle back and add some good docs, but atm I'm defering too much javadoc until things stablize... to avoid rewriting them over and over or forgetting and leaving them out of sync