Update notify_script

Returns nothing. 
The script is called, but in the email there are no warnings of indicated. 

If we replace h="${h//%w/$w}" by h="${h//%w/$warnings}" finally gets what BURP returns, with one exception: 

BURP has another bug elsewhere. on a log with 600 warnings, it shows 0 in syslog when notify_script is called, look: 

"Running notify script: testclient /var/spool/burp/testclient /var/spool/burp/testclient/0000008 2014-07-15 23:00:02 restorelog restore 0 sendmail..." 

The problem of notify_script is set with this fix, but someone should fix the second bug in BURP correctly to get the real number of warnings in the email.