python-modernize (https://github.com/mitsuhiko/python-modernize) is a
useful wrapper around 2to3 which comes with sane defaults.
The fixes below were generated by running
python-modernize --compat-unicode -w .
and then fixing all lint errors.
* Use correct username for MySQL on Travis
Travis docs say username should be 'travis', not 'root'.
* Fail test_migrations.sh if any command fails
Previously, a failing (non-zero exit code) command would not lead to
a non-zero exit code of test_migrations.sh. That meant that failing
migrations would not fail the Travis job as intended.