add a few more methods methods to hadoop-compat

migrated a few hadoop-compat methods that are used at twitter:

 * Counter.getCounter(Enum)
 * Counter.getValue()
 * JobContext.getJobID()
 * JobContext.getJobName()
 * MapContext.getInputSplit()
 * FileSystem.getDefaultBlockSize()
 * FileSystem.getDefaultReplication()
 * (hadoop2 only) FileSystem.isFileClosed()