model.py: apply int() conversion when getting capacity.
Should fix issue#19:
(sim) >>> linkinfo notodden-gw2 drammen-gw3 Information for link (notodden-gw2,drammen-gw3): name : notodden-drammen betweenness : 0.004 (4.75% of max, 38.47% of avg) capacity : 10Gbit/s load : NA utilization : NA
(sim) >>>