update robots ref: h5bp/html5-boilerplate@4e5f438e1

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>
update 404 page ref h5bp/html5-boilerplate@3da500d

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>
add google analytics code.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>
update gulp js.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>