Update init.d script template

First step to making it possible to specify Kafka heap options using attributes.
Also made it possible to configure which log4j configuration file should be used.
Cover broker configuration in unit tests

Should probably add the same type of tests in the integration suite(s).
Replace CentOS {5.9,6.4} w/ 6.5 in .kitchen.yml
Move unit tests to 'recipe' subdirectory
Fix bug in zookeeper recipe

Caused ZooKeeper to not start at all, unsurprisingly.
Prefix (private) {setup,configure} recipes with underscore (_)

See http://www.prashantrajan.com/posts/2013/06/leveling-up-chef-best-practices/ for a quick description of this convention.
Update .kitchen.yml to include (private) recipes
Remove private recipes from metadata.rb

[ci skip]
Remove private recipes from README

[ci skip]
Add heap_opts attribute for, well, configuring heap options of Kafka
Rename 'file' variable name to 'path' in configure spec
Add generic_opts attribute for general JVM settings for Kafka
Use group not user when compiling Kafka

I feel like I've done this commit before...
Add test case for including recipe in {binary,source} specs
Move all default attributes to default attributes file

Except the ones related to the zookeeper recipe.
Add nicer failure message for have_configured matcher
Update attributes related to configuration of Kafka broker

There were a whole slew of new attributes introduced in the final release of v0.8.0, as well as a few removed (metrics related).
Also handles 'map' based attributes, i.e. per topic specific attributes.

Not too happy about some of the attribute naming, so might change that in a near future, but other than that this should be good to go.
Update specs for configuration options

Managed to squash a few typo bugs as well. Still need to take care of 'map' based options, i.e. hashes transposed to CSV strings.
Update test case descriptions for configure spec
Add actual specs for previously pending examples