gulpfile, do not rebuild content when assets are modified

gulpfile.js

@@ -42,5 +42,5 @@ gulp.task('build', shell.task([
 gulp.task('default', ['webserver', 'sync', 'scss', 'gui', 'build'], function() {
   gulp.watch('./assets/css/**/*.scss', ['scss']);
   gulp.watch('./assets/css/gui.scss', ['gui']);
-  gulp.watch(['bin/build.py', './assets/css/**/*.scss', './assets/js/**/*.js', './templates/*.tpl.html'], ['build']);
+  gulp.watch(['bin/build.py', './book-src/*', './templates/*.tpl.html'], ['build']);
 });