bandwidth.sh: Added a test to check if the user is in sudoers(1)

If the agent was updated from old versions (which didn't have root
permissions), it will avoid running the bandwidth.sh script while keeping to
collect other data and send a simplified XML (equal to the UCA's and
Projectors' XML).

Signed-off-by: Erik Alexandre Pucci <eap08@c3sl.ufpr.br>
Signed-off-by: Josiney de Souza <josineys@c3sl.ufpr.br>