Fix text color of search box

Somehow the css classes of "chosen" changed from "chzn" to "chosen". This caused the search box to be "empty" (white text on white background).

assets/stylesheets/redmine_improved_searchbox.css

@@ -1 +1 @@
-#header a.chzn-single, #project_quick_jump_box_chzn { color:black; }
+#header a.chosen-single, #project_quick_jump_box_chosen { color:black; }