NEXUS-5987: Routing fixes

Changes:
* removed "applies to user managed reposes only" limitation
* removed use of ancient "validator", migrated what was needed from it
* updated logging and other issues found in class
Merge pull request #405 from sonatype/nexus-2.8.x-NEXUS-5987-routing-user-managed-reposes

[2.8.x] NEXUS-5987: Routing fixes