Update pom.xml

The build is failing with the following warning:
[WARNING] The POM for com.github.docker-java:docker-java:jar:0.9.1-SNAPSHOT is missing, no dependency information available

One warning is for a 404 on http://repo.jenkins-ci.org/public/com/github/docker-java/docker-java/0.9.1-SNAPSHOT/docker-java-0.9.1-SNAPSHOT.pom

The correct directory path should be http://repo.jenkins-ci.org/public/com/github/docker-java/docker-java/0.9.1/