categorize.cpp: Fixed character encoding conversion

The libxml2 retrieves strings using latin1 encoding. These changes will convert
the retrieved string from latin1 to standard string type.

Signed-off-by: Joaquim Junior <joaquimjuniors@gmail.com>
Acked-by: Adriano Luz <al08@c3sl.ufpr.br>
Acked-by: Josiney de Souza <josineys@c3sl.ufpr.br>