doc: refer from reference guide to introduction
CDK-318: Add a sampling morphline command that forwards each input record with a given probability to its child, and silently ignores all other input records
CDK-319: Add morphline command that ignores all input records beyond the N-th record, thus emitting at most N records, akin to the Unix head command
Merge pull request #13 from tomwhite/CDK-313-deprecate-metadata-provider

CDK-313. Deprecate MetadataProvider usages.
CDK-311. Add DatasetRepository#getUri method.
First basic DatasetOutputFormat and DatasetTarget support
Add FileSystemDataset#merge
Add a DatasetOutputCommitter that follows the commit protocol for file-based datasets.
Use NullOutputCommitter for HBase.
Create Kite Data MapReduce module.
Fix crunch target
Rebase
Use CDK-311 to get repository URI for a dataset.