SPARK-2192 [BUILD] Examples Data Not in Binary Distribution

Simply, add data/ to distributions. This adds about 291KB (compressed) to the tarball, FYI.

Author: Sean Owen <sowen@cloudera.com>

Closes #3480 from srowen/SPARK-2192 and squashes the following commits:

47688f1 [Sean Owen] Add data/ to distributions

(cherry picked from commit 6384f42ab2e5c2b3e767ab4a428cda20a8ddcbe1)
Signed-off-by: Xiangrui Meng <meng@databricks.com>
[SPARK-4661][Core] Minor code and docs cleanup

Author: zsxwing <zsxwing@gmail.com>

Closes #3521 from zsxwing/SPARK-4661 and squashes the following commits:

03cbe3f [zsxwing] Minor code and docs cleanup

(cherry picked from commit 30a86acdefd5428af6d6264f59a037e0eefd74b4)
Signed-off-by: Reynold Xin <rxin@databricks.com>