Added support for Cloudera Hadoop 4 hdfs

1. Added hdfs-plugin-vcdh4 with all code and needed jar files
2. Added test cases under hdfs-query-service/src/test.../IntegrationTest.java (please note that you will need to change the cloudera server reference for your tests)
3  Modified pom.xml to include all hdfs plugin directories
4. Modified HdfsVersion.java under hdfs-query-service to add the CDH4 references
5. Modified pom.xml under hdfs-query-service to include the cdh4 plugin
6. Added and populated repo directory under hdfs-plugin-v2 to resolve compilation errors