Use example_inputs in .travis.yml rather than ooni_inputs.

 * Fixes #8451

travis-lint checks out properly:
(ooni)∃!isisⒶwintermute:~/code/torproject/ooni-probe ∴ travis-lint
Hooray, /home/isis/code/torproject/ooni-probe/.travis.yml seems to be solid!

(ooni)∃!isisⒶwintermute:~/code/torproject/ooni-probe ∴ date
Mon Mar 11 20:22:20 UTC 2013