avro

Squashed commit of the following:

commit a3f86c2874ad6d86b11fc2edc908065adcefdeda
Author: Daniel Kulp <dkulp@apache.org>
Date:   Tue Nov 20 14:32:48 2018 -0500

    Grab some more tests from other PR

commit 7d7822b5960c157ddf6db7fa15a3d797d0b286ee
Author: Joseph Pachod <joseph.pachod@berger-levrault.fr>
Date:   Sun Dec 11 22:50:45 2016 +0100

    new javadoc with same formatting as other javadoc

commit 82e8f7af6736034f4e85a4e6e1bcaa803019082e
Author: Joseph Pachod <joseph.pachod@berger-levrault.fr>
Date:   Sun Dec 11 22:38:33 2016 +0100

    restore initial imports

commit 0ca9815c8c884bc30c73b5c8a3c5d4c6e5188cee
Author: Joseph Pachod <joseph.pachod@berger-levrault.fr>
Date:   Sun Dec 11 22:36:03 2016 +0100

    javadoc

commit 551e1eb4a6bdedf00260ef90576490648f9b4658
Author: Joseph Pachod <joseph.pachod@berger-levrault.fr>
Date:   Wed Dec 7 23:14:03 2016 +0100

    format and clarify pre existing tests

commit 857da0c70a2db321d5bf521b901fe0c035f32edc
Author: Joseph Pachod <joseph.pachod@berger-levrault.fr>
Date:   Wed Dec 7 22:53:13 2016 +0100

    AVRO-1961: Java: add isUnion and isNullable on Schema class

Closes #169