[web2py] fix for truncate in SQLTABLE for new implement dict

[Carlos]

Hi,

Here's a fix for truncate in SQLTABLE for "new implement dict", such that it 
truncates only when necessary.

Line 1,469 in SQLTABLE.__init__ in sqlhtml.py

- if isinstance(headers[colname]['truncate'], int):
+ if isinstance(headers[colname]['truncate'], int) and len(ur) > 
headers[colname]['truncate']:

Thanks,

   Carlos