Add link to latest Kafka doc. in README
Add `amazon` to supported OSes

It’s essentially CentOS, but since I’ve been testing this cookbook
on EC2 with instances running Amazon Linux I might as well add it, as
it seems like a thing people do.
Respect `controlled.shutdown.enable` in init scripts

Basically don’t force-kill the Kafka process if `controlled.shutdown.
enable` is set to true. While it’s not necessarily a problem to force-
kill the process, it does take quite some time to verify all the logs
when it starts up again, and sort of defeats the purpose of even setting
the option in the first place.

From what I can tell from the upstart documentation it doesn’t try to
kill an application if it doesn’t shutdown from the first signal, though
I haven’t verified that this is the case.
Merge branch 'controlled-shutdown'
Add int. tests for pidfile creation/removal
Wait indef. for a controlled shutdown for RedHat distros

Thought it would be a lot nicer to actually wait for Kafka to shutdown
when `controlled.shutdown.enable` is set to `true`, so that one can use
the `restart` action.

Unfortunately I had to write a simplified version of `killproc` to
actually get this to work. I hate init scripts.
Wait indef. for a controlled shutdown on Debian

If I understand the documentation for `start-stop-daemon`, giving a
`—signal` parameter it won’t force-kill a process.
Update `.kitchen.docker.yml`
Remove duplicate mention of supported versions in README

[ci skip]
These changes add in ulimit for file descriptors.

For #56
Making default for ulimit_file nil.
It'll only apply if you set it.
For #56.
Remove `non-nil` checks for `ulimit_file` option

Not really necessary. If one set’s it to `false`, it’s their problem.
Add int. test(s) for `ulimit_file` option

Definitely not the prettiest tests I’ve written, but they do the job.
Merge branch 'solarce-ulimit-support'
Remove spurious newline in debian init template
Version bump to v0.6.0
Add serverspec specific Gemfile to int. tests

Otherwise all hell breaks loose. Probably have to migrate tests and
whatnot in the near future, but for now it’d be nice to actually be
able to run the integration tests that are in place.
Add support for systemd as an `init_style`

First stab at getting `systemd` to work. Still not sure about a few
things such as using an EnvironmentFile and the code for setting up
everything related to init styles is even messier, so it could probably
use some cleanup and rethinking.

Also added a`systemd?` helper for integration tests, as the current
version of serverspec that is used is unable to check if a service is
enbaled for distros that use systemd, so until there's a better fix
this'll have to to.
Fixup of env. file for systemd

Add explicit filename for the log4j and server properties, cleanup
unused ERB tags and fix JXM_PORT tag.
Merge branch 'brigade-systemd-support'