error based sqli plugin

based on @Zigoo0's WebPwn3r
usage:
Bywaf> use sqli
Bywaf/sqli> test test http://127.0.0.1/sqli.php?search=a
running with: http://127.0.0.1/sqli.php?search=a
[*] Bingo! Vulnerable url: http://127.0.0.1/sqli.php?search=a3' 
[*] Bingo! Vulnerable url: http://127.0.0.1/sqli.php?search=a3%5c