karma: Use 'minimal' rather than 'errors-only' for stats (#952)
karma: Use 'minimal' rather than 'errors-only' for stats (#952)

Since otherwise warnings are not even printed (such as those that are
emitted by `eslint-loader` when `failOnError` is `false`).
mozilla-neutrino/neutrino-dev,mozilla-neutrino/neutrino-dev,edmorley/neutrino-dev,edmorley/neutrino-dev