Merge pull request #63 from pwendell/master

Fixing spark streaming example and a bug in examples build.

- Examples assembly included a log4j.properties which clobbered Spark's
- Example had an error where some classes weren't serializable
- Did some other clean-up in this example
(cherry picked from commit 28e9c2abc0884d096fc3be1e2d1f9ee18ffc3261)

Signed-off-by: Patrick Wendell <pwendell@gmail.com>