Fix drone service (droned) from starting without droned_opts (with tests).

When writing a wrapper cookbook for Drone using this CK I discovered that no matter what options were set in `droned_opts` the drone service (droned) would start with the defaults e.g. `droned --port=:80`.

After a little big of digging a realised that custom settings were included in the config file as expected and a simple `service drone restart` would do the trick.

This PR adds tests to make sure that the `droned` process has indeed been started with the options set as attributes as well as my fixes that were necessary within the recipe.
Some of my Vagrant boxes are using Chef 10 still. Can we keep `require_chef_omnibus` in the `driver_config` at the top of the file?