`def` font-locking applied to namespaced keywords inside parens

[codonnell]

In a clojure buffer (:foo/def bar baz) is highlighted much like (def bar baz) rather than taking the keyword font.

I'm running:

• GNU Emacs 24.5.1 (x86_64-pc-linux-gnu, GTK+ Version 3.16.6) of 2015-09-17 on lgw01-52, modified by Debian
• clojure-mode (version 5.2.0)
• Ubuntu 15.10