go.talks/present: move included js files outside of static directory

When deployed to App Engine, directories listed in app.yaml
static_files directives are inaccessible to the running application.
This change allows the /play.js handler to read these JS files.

R=campoy, campoy, dsymonds
CC=golang-dev
https://golang.org/cl/7309054
diff --git a/present/appengine.go b/present/appengine.go
index ef620ed..ccec452 100644
--- a/present/appengine.go
+++ b/present/appengine.go
@@ -23,7 +23,7 @@
 var basePath = "./present/"
 
 func init() {
-	playScript("/static/jquery.js", "/static/playground.js")
+	playScript(basePath, "jquery.js", "playground.js")
 	present.PlayEnabled = true
 	http.HandleFunc("/compile", compile)
 }
diff --git a/present/static/jquery.js b/present/js/jquery.js
similarity index 100%
rename from present/static/jquery.js
rename to present/js/jquery.js
diff --git a/present/static/play.js b/present/js/play.js
similarity index 100%
rename from present/static/play.js
rename to present/js/play.js
diff --git a/present/static/playground.js b/present/js/playground.js
similarity index 100%
rename from present/static/playground.js
rename to present/js/playground.js
diff --git a/present/static/socket.js b/present/js/socket.js
similarity index 100%
rename from present/static/socket.js
rename to present/js/socket.js
diff --git a/present/local.go b/present/local.go
index e655352..8674dfd 100644
--- a/present/local.go
+++ b/present/local.go
@@ -15,6 +15,6 @@
 // HandleSocket registers the websocket handler with http.DefaultServeMux under
 // the given path.
 func HandleSocket(path string) {
-	playScript("/static/socket.js")
+	playScript(basePath, "socket.js")
 	http.Handle(path, socket.Handler)
 }
diff --git a/present/play.go b/present/play.go
index 9a0682a..fcd361d 100644
--- a/present/play.go
+++ b/present/play.go
@@ -14,11 +14,11 @@
 
 // playScript registers an HTTP handler at /play.js that contains all the
 // scripts specified by path, relative to basePath.
-func playScript(path ...string) {
+func playScript(root string, path ...string) {
 	modTime := time.Now()
 	var buf bytes.Buffer
-	for _, p := range append(path, "/static/play.js") {
-		b, err := ioutil.ReadFile(filepath.Join(basePath, p))
+	for _, p := range append(path, "play.js") {
+		b, err := ioutil.ReadFile(filepath.Join(root, "js", p))
 		if err != nil {
 			panic(err)
 		}