Upgrade to a modern leiningen

lein we were using was almost 2 years old. This also resolves a warning
we were getting from using 1.7 and old dependencies:

cat already refers to: #'clojure.core/cat in namespace

Author: cldwalker

runner/project.clj

@@ -3,8 +3,7 @@
   :license {:name "Eclipse Public License"
             :url "http://www.eclipse.org/legal/epl-v10.html"}
   :dependencies [[org.clojure/clojure "1.7.0"]
-                 [leiningen "2.3.4"
-                  :exclusions [stencil]]
+                 [leiningen "2.5.2" :exclusions [stencil]]
                  [fs "1.3.3"]]
   :uberjar-name "lein-light-standalone.jar"
   :profiles {:uberjar {:aot :all}}