DateTransform serializes as a number instead of string. The deserializer was already considering this case. Adds millisecond precision to DateTransform
Calls rake test[all] using bundle exec since CI was failing

https://travis-ci.org/emberjs/data/builds/16487436
Merge pull request #1613 from MiguelMadero/millisecond-precission-to-date-serialize

Adds millisecond precission to DS.DateTransform