[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