Fix findbugs

Signed-off-by: Lee Sheng <lsheng@wibidata.com>
KIJIMR-8. Mark all kiji-mr classes with audience annotations.

This commit marks all classes in packages org.kiji.mapreduce.* with
audience annotations.

Signed-off-by: Aaron Kimball <aaron@wibidata.com>
KIJIMR-4. Remove org.kiji.mapreduce.tools.RequiredFlagException

This commit removes RequiredFlagException from kiji-mapreduce, because
it already exists in kiji-schema.  All usages of this exception in
kiji-mapreduce have been modified to depend on the class in kiji-schema.

Signed-off-by: Christophe Taton <taton@wibidata.com>