pom.xml: update avro dependency

Signed-off-by: Francis Galiegue <fgaliegue@gmail.com>
More updates to Avro

Signed-off-by: Francis Galiegue <fgaliegue@gmail.com>
Add tests with original test files from the Apache Avro svn

All of them work!

I just had to remove tests with dependencies on other, external schemas since
this is not handled yet.

Signed-off-by: Francis Galiegue <fgaliegue@gmail.com>