Fix keywords and symbols in :class

Fixes #367

src/reagent/impl/template.cljs

@@ -122,12 +122,14 @@
       ;; Merge classes
       class
       (assoc :class (let [old-class (:class props)]
-                      (if (nil? old-class) class (str class " " old-class)))))))
+                      (if (nil? old-class) class (str class " " (name old-class))))))))
 
 (defn stringify-class [{:keys [class] :as props}]
+  ;; (keep name) doesn't work because class vector could contain false, which is not Named
   (if (coll? class)
     (->> class
          (filter identity)
+         (map name)
          (string/join " ")
          (assoc props :class))
     props))

test/reagenttest/testreagent.cljs

@@ -574,6 +574,22 @@
   (is (= (rstr [:p {:class #{"a" "b" "c"}}])
          (rstr [:p {:class "a b c"}]))))
 
+(deftest class-named-values
+  (is (= (rstr [:p {:class :a}])
+         (rstr [:p {:class "a"}])))
+  (is (= (rstr [:p.a {:class :b}])
+         (rstr [:p {:class "a b"}])))
+  (is (= (rstr [:p.a {:class 'b}])
+         (rstr [:p {:class "a b"}])))
+  (is (= (rstr [:p {:class [:a :b]}])
+         (rstr [:p {:class "a b"}])))
+  (is (= (rstr [:p {:class ['a :b]}])
+         (rstr [:p {:class "a b"}])))
+
+  (testing "class collection can contain false value"
+    (is (= (rstr [:p {:class [:a :b false nil]}])
+           (rstr [:p {:class "a b"}])))) )
+
 (deftest test-force-update
   (let [v (atom {:v1 0
                  :v2 0})