TAJO-616: SequenceFile support. (jaehwa)
TAJO-730: Update Tajo site to reflect graduation.
Add missed ASF feather logo.
TAJO-711: Add boilerplate Avro appender and scanner.
TAJO-711: Add Avro storage type to tests. Add boilerplate code to AvroAppender and AvroScanner.
TAJO-711: Add package-info.java and start fleshing out AvroAppender.