Switch travis build to O1 optimization to reduce test runtime
Switch travis build to O1 optimization to reduce test runtime

srange/SU2,drewkett/SU2,drewkett/SU2,drewkett/SU2,drewkett/SU2,srange/SU2,hlkline/SU2,hlkline/SU2,srange/SU2,hlkline/SU2,drewkett/SU2,hlkline/SU2,hlkline/SU2,srange/SU2