add support for hdfs integration
changes per review:

* `supports` python vs. `depends`
* `include_recipe "python"` vs. install packages
* add comments for hdfs instances format
ignore the FC rule for this particular condition

Since we wish to allow users to make the best choices, leaving some of
the external Chef requirements up to the user to handle instead of
mandating that they use a particular version of a dependency cookbook.

This was further discussed in DataDog/chef-datadog#77
change supports to suggests for operator view
update changelog for hdfs contribution [ci skip]