ga4gh/ReadTaskTeam — pull request #29 by fnothaft (2014-04-26 17:02:51+00:00)
Title: Cleaned up array fields in avro schema.

This change updates all:

```
union { null, array<*> } ... = null;
```

fields in the current schema to:

```
array<*> ... = [];
```

It is unnecessary to make the avro collection fields nullable, as long as the default value is set to the empty collection. This will make the schema easier to maintain over time, and simpler to read.