Installer: Refactor and give each searver its own directory

Change-Id: I1db2929e7a35b6f92022dec0c6506d68e0297563
diff --git a/core/installer/server/caching_handler.go b/core/installer/server/caching_handler.go
new file mode 100644
index 0000000..3d31c25
--- /dev/null
+++ b/core/installer/server/caching_handler.go
@@ -0,0 +1,18 @@
+package server
+
+import (
+	"net/http"
+)
+
+type cachingHandler struct {
+	h http.Handler
+}
+
+func NewCachingHandler(h http.Handler) http.Handler {
+	return cachingHandler{h}
+}
+
+func (h cachingHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Cache-Control", "max-age=604800")
+	h.h.ServeHTTP(w, r)
+}