(This follows from a side point on SPARK-1133, in discussion of the PR: https://github.com/apache/spark/pull/164 )

Commons IO is barely used in the project, and can easily be replaced with equivalent calls to Guava or the existing Spark `Utils.scala` class.

Removing a dependency feels good, and this one in particular can get a little problematic since Hadoop uses it too.

Author: Sean Owen <sowen@cloudera.com>

Closes #226 from srowen/SPARK-1316 and squashes the following commits:

21efef3 [Sean Owen] Remove use of Commons IO