hadoop-hdfs-client JAR does not include ConfiguredFailoverProxyProvider

The hadoop-client POM now includes a leaner hdfs-client, stripping out all the transitive dependencies on JARs only needed for the Hadoop HDFS daemon itself. The specific jars now excluded are: leveldbjni-all, jetty-util, commons-daemon, xercesImpl, netty and servlet-api. This should make downstream projects dependent JARs smaller, and avoid version conflict problems with the specific JARs now excluded. Applications may encounter build problems if they did depend on these JARs, and which didn't explicitly include them. There are two fixes for this * explicitly include the JARs, stating which version of them you want. * add a dependency on hadoop-hdfs. For Hadoop 2.8+, this will add the missing dependencies. For builds against older versions of Hadoop, this will be harmless, as hadoop-hdfs and all its dependencies are already pulled in by the hadoop-client POM.