CDK-488: Add Job instantiation to Hadoop compat.

This also updates DynConstructors so that the constructor class is a
DynMethod and can be used as a method implementation. This was needed
because the constructor for Job has been deprecated in favor of
Job.getInstance, so one alternative needs to be a constructor and the
other a method.
CDK-488: Update to 2.3.0 to make copy test pass.

This updates to hadoop 2.3.0 so that the LocalJobRunner uses more than
one reducer and passes when we check that the correct number of files
are created. This uses the LocalJobRunner.setLocalMaxRunningReduces, and
does not run the test if it is not present so that the test is ignored
in the cdh4 and hadoop-1 profiles.