update html5 boilerplate file.

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

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>
add grunt-html-validation plugin and fix some html error.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>
ignore html validation error report.

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