Update to Flink 1.8.3

Also, some general Dockerfile updates.

library/flink

@@ -4,22 +4,22 @@ Maintainers: Patrick Lucas <[email protected]> (@patricklucas),
              Ismaël Mejía <[email protected]> (@iemejia)
 GitRepo: https://github.com/docker-flink/docker-flink.git
 
-Tags: 1.8.2-scala_2.11, 1.8-scala_2.11
+Tags: 1.8.3-scala_2.11, 1.8-scala_2.11
 Architectures: amd64
-GitCommit: a1c7fec05760b20a48ace3861874f90b6df9f396
+GitCommit: 4d85b71b7cf9fa4a38f8682ed13aa0f55445e32e
 Directory: 1.8/scala_2.11-debian
 
-Tags: 1.8.2-scala_2.12, 1.8-scala_2.12, 1.8.2, 1.8
+Tags: 1.8.3-scala_2.12, 1.8-scala_2.12, 1.8.3, 1.8
 Architectures: amd64
-GitCommit: a1c7fec05760b20a48ace3861874f90b6df9f396
+GitCommit: 4d85b71b7cf9fa4a38f8682ed13aa0f55445e32e
 Directory: 1.8/scala_2.12-debian
 
 Tags: 1.9.1-scala_2.11, 1.9-scala_2.11, scala_2.11
 Architectures: amd64
-GitCommit: a1c7fec05760b20a48ace3861874f90b6df9f396
+GitCommit: 8cd66b6f89c13134270a4e865a40c2e5e72cfa21
 Directory: 1.9/scala_2.11-debian
 
 Tags: 1.9.1-scala_2.12, 1.9-scala_2.12, scala_2.12, 1.9.1, 1.9, latest
 Architectures: amd64
-GitCommit: a1c7fec05760b20a48ace3861874f90b6df9f396
+GitCommit: 8cd66b6f89c13134270a4e865a40c2e5e72cfa21
 Directory: 1.9/scala_2.12-debian