[packaging] refactor packaging to avoid fat-jars.

• remove unused declared deps in a few places
• lex sort modules in top level pom
• update maven plugin versions.
• no more jar-with-dependencies
• set ycsb-core to provided in bindings
• introduce a bindings-parent pom that sets
  • stage dependency copy on building binding
  • iff binding has a README.md, build a binding-specific dist artifact
• update distribution assembly to
  • properly build after modules
  • use per-binding sets of dependencies

closes #250