Use dot reporter as default mocha reporter
Use dot reporter as default mocha reporter

(The original default spec does not scale when we have a lot of test.  With this way, we are also more encourage to test or at least consume warning.)

uwdata/vega-lite,uwdata/vega-lite,uwdata/vega-lite,vega/vega-lite,vega/vega-lite,vega/vega-lite,uwdata/vega-lite,vega/vega-lite,vega/vega-lite,uwdata/vega-lite