move bijection-x modules out

[johnynek]

The many modules, especially those with scala dependencies, create pains to publish new versions (e.g. #285 ) since we need all the scala library dependencies to be published first.

I think we should reverse the dependency graph: if bijection-util is useful, it should be merged into the util repo. Similarly with scrooge.

cc @mosesn

[mosesn]

@johnynek like bijection, util-core has ~no dependencies. it probably makes more sense to split it out into its own repo rather than having it live in one or the other.

[johnynek]

Note, bijection-clojure is basically never used according to maven central statistics. We could probably remove that module and make life a bit simpler.

Then maybe get twitter to make a new project bijection-util which can depend on both bijection and util so one won't block the other. Since bijection-util depends on very stable APIs, it usually won't need to be updated anyway.