Indent clojure.spec/fdef differently (#476)

```clj
;; before
(s/fdef ::uhhuh
        :args (s/keys :req [::hello])
        :ret any?)

;; after
(s/fdef ::uhhuh
  :args (s/keys :req [::hello])
  :ret any?)
```

Author: ghadishayban

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## master (unreleased)
 
+* Indent `fdef` (clojure.spec) like a `def`.
+
 ## 5.7.0 (2018-04-29)
 
 ### New features

clojure-mode.el

@@ -1515,6 +1515,7 @@ work).  To set it from Lisp code, use
   (locking 1)
   (proxy '(2 nil nil (:defn)))
   (as-> 2)
+  (fdef 1)
 
   (reify '(:defn (1)))
   (deftype '(2 nil nil (:defn)))