SPARK-1935: Explicitly add commons-codec 1.5 as a dependency.

Author: Yin Huai <huai@cse.ohio-state.edu>

Closes #889 from yhuai/SPARK-1935 and squashes the following commits:

7d50ef1 [Yin Huai] Explicitly add commons-codec 1.5 as a dependency.
(cherry picked from commit 60b89fe6b09ff896a30d74204876da883e307de7)

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