Handle comment char, empty line, escape \t \r \n \\

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
Ship a sample commit message file: snippet.txt

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
Update documentation about commit message snippet

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>