Upgrade greylog-slf4j to SLF4J v2
Fix published artifacts (2.5.1 included root POM and BOM excluded greynaf-dns)
Build with Java 8 (2.5.1 accidentally uploaded Java 11 artifacts)
Published to Maven Central as com.github.greysoft.naf:X:2.5.2, with dependency on greybuild 2.0.3