SAMZA-152 Add samza-kv example to wikipedia-stats

Original version in bd72e3cd56296c07447c2eeeba586564a89494fd was
reverted after an accidental merge.
SAMZA-152 Run a single task per job by default

See discussion on https://issues.apache.org/jira/browse/SAMZA-152
Merge pull request #33 from ept/SAMZA-152

SAMZA-152 Add samza-kv example to wikipedia-stats