clojure-mode.el (clojure-docstring-fill-column): Use `fill-column' as the default value

* clojure-mode.el (clojure-docstring-fill-column): Use
`fill-column' as the default value.
Merge pull request #233 from bzg/master

clojure-mode.el (clojure-docstring-fill-column): Use `fill-column' as th...