Fixes #75

Changed spec to reproduce the error. It only manifested itself when the
missing attribute was the direct descendant of an existing one.
Merge pull request #76 from jhosm/fix-issue-75

Fixes #75
Add DSL method for data_bag_item_for_environment.

In my opinion there are some legitimate cases where we want environment
data bags that are not encrypted. We are using this for storing
ephemeral information created at the time of the Chef run (for example,
user public keys for continuous integration accounts).
Update the README with appropriate reference.
Merge pull request #81 from johnbellone/master

Add DSL method for data_bag_item_for_environment.