Add `automatic_start` attribute

When set to true, `:start` will be added to the `action` array that is
given to the kafka service definition.
Restart kafka on server configuration file change

One could argue that it should restart if env configuration file changes
as well, and probably log4j configuration. Coming up next.
Additional configuration to consider for automatic restart

* /opt/kafka/log4j.properties
* /etc/init.d/kafka
* /etc/sysconfig/kafka

And the corresponding files depending on platform and init style.
Start kafka automatically if `automatic_restart` is set

Now, I’m not a fan of starting / restarting things automatically as it
tends to break things, but this feels quite natural to me. No?
`automatic_restart` implies `automatic_start`

Reasoning stated in the comment.
Merge branch 'automatic-start-restart'

Closes #42.
Update development dependencies
Reorder automatic_{start,restart} test & update test description
Version bump to v0.4.0
Add missing comment for `log.dirs` attribute

[ci skip]
Create `log.dirs` directories in `_setup` recipe

Not really sure how I missed this before, because this feels like
something that should really be done, right?
Add integration tests for creating `log.dirs`
Merge branch 'create-log-dirs'
Version bump to v0.4.1

I’d consider this a patch release due to the fact that this should’ve
been done since the start, and I’m a bit surprised that no-one has filed
an issue about it. Suppose that’s because Kafka actually create the log
directories and then it’s not a big deal.
Use new ChefSpec.start! method for coverage reporting
Remove setup of ZooKeeper

Setting up ZooKeeper is well beyond the scope of this cookbook, as it’s
only intention is to set up Kafka brokers. It’s also _NOT_ recommended
to set up ZooKeeper on the same hardware that Kafka is running on, for
quite obvious reasons.

Maintaining the current / previous ZooKeeper while this cookbook is
transitioning to a more dynamic approach to configuration files is going
to be a lot more difficult and most likely introduce complexity and
exceptions that wouldn’t be needed if this cookbook only set up Kafka.
Rename `kafka.env.erb` template
Simplify `kafka_init_opts` helper method

Don’t need it to be “configurable” anymore.
Remove String interpolation in `default` recipe
Merge branch 'remove-zookeeper-recipe'