Update .travis.yml (#680)
Update .travis.yml (#680)

10.3 is not available. Instead use 10.3.1.

See https://travis-ci.org/jverkoey/nimbus/jobs/311646947 for the error this CL fixes.
Arcank/nimbus,jverkoey/nimbus,Arcank/nimbus,jverkoey/nimbus,Arcank/nimbus,Arcank/nimbus,jverkoey/nimbus,Arcank/nimbus,jverkoey/nimbus,Arcank/nimbus,jverkoey/nimbus,jverkoey/nimbus,Arcank/nimbus,jverkoey/nimbus