Travis CI config maintenance (#133)
Travis CI config maintenance (#133)

- `sudo` key has been deprecated.
- Split out sign-off check into a separate job so that it is performed only once.
- Give descriptive names to jobs.

libtuv-DCO-1.0-Signed-off-by: Akos Kiss akiss@inf.u-szeged.hu
Samsung/libtuv,Samsung/libtuv,Samsung/libtuv