Ram Kumar K R

Hi All, I was trying out backburner for a rails project and observed that the tests were failing on my machine and also on [travis](https://travis-ci.org/nesquena/backburner/jobs/125132312) since this [pull request](https://github.com/nesquena/backburner/pull/123) has...

- Remove printing of Default Tube stats whether Getstats returns data for it or not - Remove the special condition to continue for default tube More details on https://github.com/src-d/beanstool/issues/17#issuecomment-426486670

- Use ActiveRecord keys instead of looking up from rails database config Reference: http://stackoverflow.com/a/14044420/2623762