Feature/continuous integration

See the first git commit message on this branch. I am too sleepy to copy/paste it.

The tests for the file check out fine:
```
?!isis?wintermute:~/code/torproject/ooni-probe ? travis-lint
Hooray, /home/isis/code/torproject/ooni-probe/.travis.yml seems to be solid!
```

Please merge so that I can continuing testing the CI. Thanks! <3