PORTLAND — Portland-based Nutcase Inc., which makes stylish head protectors for urban bicyclists, has a new owner. Bravo Sports Corp. announced the purchase Thursday; terms were not disclosed. The deal comes a few months after the California company added Sector 9 and Pro-Tec — which make skateboards and skate gear — to its stable of recreational and sporting goods brands. Former Nike creative director Michael Morrow founded Nutcase in 2006 with Miriam Berman.