Also got rid of some type warnings.
Also cleaned up the AvroJob class and added some comments.
An input format that reads from Avro container files. The Avro container files are required to contain generic records, each with exactly two fields: 'key' and 'value'. The key and value fields from the generic record will be read as the MR job's input key and value as expected. This reads files generated by the AvroKeyValueOutputFormat.