Update ChefSpec to v3.4.0
Tidy up unit tests a wee bit
Remove (pointless) `not_if` from `_setup` recipe

Let Chef do its thing.
Prefix name of validate block in `kafka_download` w/ 'kafka'

Global namespaces are global, let's try to keep things isolated to some
extent.
Update `base_url` for downloading archives

Not really 100% satisfied with this solution at all. Probably need to
contact the Kafka team regarding *where* we (people using Chef) are supposed to fetch the archives / packages from. And I'll add a note to
the README that people should keep archives hosted locally as well.
Fix incorrect test description in tests for source recipe
Update tests for `default` recipe to *actually* terminate the Chef run
Set `install_method` to :source in tests for source recipe
Select archive extension based on `version` and `install_method`

I hate myself for this, and I'm pretty sure some kittens died in the
making of this code.
Prefer `%()` over double quotation marks (`""`)
Remove `build` as root

Because reasons. Fuck.
Extract `kafka_src` to helper method
Add hackyish support for building Kafka v0.8.1 from source

Maaaan, this fucking mess I tell you. v0.8.1 switched from 'sbt' to 
'gradle', and it was just a cluster fuck to actually construct a
'release' tar.gz archive. Google is my best friend, always and forever.

I'm not happy about this current solution, and I'm not done with it yet.
There's plenty of room for improvement and making things pretty.
Just you wait.
Extract `kafka_target_path` to helper method
Update service related integration tests to be less picky

v0.8.1 doesn't log the same messages as v0.8.0 (for some reason), there's
been changes to capitalisation and whatnot.
Update default kafka and scala versions

* kafka, v0.8.0 -> v0.8.1
* scala, v2.8.0 -> v2.9.2

The future is now, deal with it.
Bump ZK connection timeout in .kitchen.yml
Update default kafka version to v0.8.1.1

Really need to fix the tests to be less annoying when updating versions.
Add new `log` related attributes for kafka > v0.8.0
Add new `advertised` attributes for kafka > v0.8.0