Fix ns requires - compojure.core

The compojure template required the compojure.core library by referring all
 functions from that namespace.  While this does give convienience of just using
 the function name without a namespace, it does mean many functions not used are
 included.

(ns status-monitor.handler
  (:require [compojure.core :refer :all]))

Using this form also raises a warning from the Joker linting tool that I have
running in Spacemacs.

To be more specific when using the compojure.core library, I changed the require
 to refer the specific functions / macros used, defroutes and GET

 (:require [compojure.core :refer [defroutes GET]]

Stating exactly which functions you are using from each library helps with
maintaining the code as well as minimising unknown conflicts.

src/status_monitor/handler.clj

@@ -1,5 +1,5 @@
 (ns status-monitor.handler
-  (:require [compojure.core :refer :all]
+  (:require [compojure.core :refer [defroutes GET]]
             [compojure.route :as route]
             [ring.middleware.defaults :refer [wrap-defaults site-defaults]]
             [hiccup.core :refer :all]