More post-1.9 cleanup

[alexander-yakushev]

Some things that slipped past me in the 1.9 removal cleanup.

Also, remove handling of obscure clojure.spec namespace which only existed in some 1.9 alphas.

[bbatsov]

This has always been very funny to me:

;; - clojure.spec (released between Clojure 1.8 and 1.9, but never included in Clojure) ;;
;; - clojure.spec.alpha (renamed from clojure.spec and included in Clojure 1.9)         ;;
;; - clojure.alpha.spec (spec-2, the new experimental version)                 

Brilliant naming! 😆