fix toString()' is ambiguous' error message in build

please accept my short fix to a build error i got trying your latest code. yet i couldn't get to test drive your application as it  core dumped while I opened my browser on the app
[2014-Aug-19 19:58:36.942781] 32747 [/ udGyzQXMmkoPz3SZ] [start] " *** HitSession::Update()  *** Path = /"
Erreur de segmentation (core dumped)
Could you put somewhere how you  start your   app.
I did ./WittyWizard.wt --approot app_root --docroot .  --http-address=0.0.0.0 --http-port=8092.
btw i have a much smaller project going on if you are on skype we could team up. just let me know here or lyase.d@gmail.com