[SS-215] Adds data_bags directory to recipes archive

http://tickets.engineyard.com/issue/SS-215

- Why was the change necessary?
We have customers on the old UI who want encrypted data bags support
but the current way to do it requires creating the archive manually.

- How does the change address the issue?
This checks for the presence of the "data_bags" directory as a sibling
of the "cookbooks" directory and if found, adds it to the archive.

- What side effects/risks does this change have?
This should only affect the recipes upload functionality but it should
be pretty safe.

- What test scenarios were (or will be) used to validate change
I made sure that all current specs were still green after this change
and then tested that on a live environment, I'm able to find the
data_bags directory in /etc/chef-custom/recipes