Leave one blank line below 'private'

More readable and eye appealing ;)

According to: ruby-style-guide ( https://github.com/bbatsov/ruby-style-guide/blob/master/README.md#classes--modules )

` Leave one blank line above the visibility modifier and one blank line below in order to emphasize that it applies to all methods below it.`
Merge pull request #1147 from Bartuz/patch-1

Leave one blank line below 'private'
Fix Travis CI
Merge pull request #1150 from Shopify/fix_travisci

Fix Travis CI