add attachEvent.js

Signed-off-by: arcticlion <david.malan@aol.com>
attachEvent()事件处理程序在全局作用域中运行

Signed-off-by: arcticlion <david.malan@aol.com>
attachEvent按添加的相反顺序触发

Signed-off-by: arcticlion <david.malan@aol.com>
write a Method of detachEvent in attachEvent.js

Signed-off-by: arcticlion <david.malan@aol.com>
add addHandler.js

Signed-off-by: arcticlion <david.malan@aol.com>
add removeHandler() in addHandler.js

Signed-off-by: arcticlion <david.malan@aol.com>
write a Usage of EventUtil in addHandler.js

Signed-off-by: arcticlion <david.malan@aol.com>