Duplicated storybook bundles

[alcferreira]

Looks like after upgrading storybook to the latest version, we are commiting all the bundles under docs folder.
Previously it used to remove the old ones and add the new ones: 8fd50ef, 64d27cc

And now it just adds the new ones: bf98c56, 03d827b

The responsible lines for these commits are: https://github.com/CraveFood/farmblocks/blob/master/.travis.yml#L44-L47