Ignore RateLimitedOutputStreamSuite for now.

This test has been flaky. We can re-enable it after @tdas has a chance to look at it.

Author: Reynold Xin <rxin@apache.org>

Closes #54 from rxin/ratelimit and squashes the following commits:

1a12198 [Reynold Xin] Ignore RateLimitedOutputStreamSuite for now.
SPARK-1084.2 (resubmitted)

(Ported from https://github.com/apache/incubator-spark/pull/650 )

This adds one more change though, to fix the scala version warning introduced by json4s recently.

Author: Sean Owen <sowen@cloudera.com>

Closes #32 from srowen/SPARK-1084.2 and squashes the following commits:

9240abd [Sean Owen] Avoid scala version conflict in scalap induced by json4s dependency
1561cec [Sean Owen] Remove "exclude *" dependencies that are causing Maven warnings, and that are apparently unneeded anyway