Datomic 0.8.4159

I know you guys generally don't want free/pro licensed software in homebrew (except mysql), but installing datomic can be pain in the ass (need to set path, script name clashes, running transactor etc.). I treat Datomic Free as interesting research DB. I think this formula will save some time for other people.

For good start I wrote installing datomic to libexec and exporting commands prefixed by `datomic-`:

    datomic datomic-repl datomic-repl-jline datomic-rest datomic-shell datomic-transactor

I think transactor daemon can wait until there's such demand.

Generally should fix #21846