Maven assembly plugin crashes JDK 9 build

Currently we use assembly plugin in version 2.6 which crashes JDK 9 build because it internally uses old plexus archiver version.
All this boils down to JEP-223 (better known as project Verona) which changed the Java version string from "1.8" to "9".

Solution is to:

• Update assembly plugin to 3.0.0 (preferable)
• Keep 2.6 and update its dependency on plexus archiver to 3.0.3
  • Only if we for some reason need to keep older version (unlikely)