Replace :javac-options map with vector. Fixes #450.

sample.project.clj

@@ -149,7 +149,7 @@
   :uberjar-name "sample-standalone.jar" ; as above for uberjar
   ;; Options to pass to java compiler for java source
   ;; See http://ant.apache.org/manual/Tasks/javac.html
-  :javac-options {:destdir "classes/"}
+  :javac-options [:destdir "classes/"]
   :java-source-paths ["src/main/java"] ; location of Java source
   ;; Leave the contents of :source-path out of jars (for AOT projects)
   :omit-source true

src/leiningen/javac.clj

@@ -28,7 +28,7 @@
   [project files args]
   (into-array
    String
-   (concat (:javac-options project)
+   (concat (map name (:javac-options project))
            args
            ["-cp" (classpath/get-classpath-string project)
             "-d" (:compile-path project)]