Feature/unit tests

This adds a bunch of unit tests, using chefspec. My goal is to get 100% code coverage, or as close to 100% as possible.

Currently testing these recipes:
- default
- hadoop_hdfs_datanode hadoop_hdfs_journalnode hadoop_hdfs_namenode hadoop_hdfs_secondarynamenode hadoop_hdfs_zkfc
- hadoop_mapreduce_historyserver
- hadoop_yarn_nodemanager hadoop_yarn_proxyserver hadoop_yarn_resourcemanager
- hbase hbase_master hbase_regionserver hbase_rest hbase_thrift
- pig
- zookeeper zookeeper_server

```
Finished in 8.39 seconds
73 examples, 0 failures

ChefSpec Coverage report generated...

  Total Resources:   76
  Touched Resources: 70
  Touch Coverage:    92.11%
```