Fixed because the bundler version depends on the Travis CI spec.
Fixed because the bundler version depends on the Travis CI spec.

Travis CI log
```
Bundler could not find compatible versions for gem "bundler":
  In Gemfile-rspec-3.7.x:
    bundler (~> 1.3)
  Current Bundler version:
    bundler (2.0.2)
```

gongo/turnip_formatter,gongo/turnip_formatter,gongo/turnip_formatter