Enable the Broadcast examples to work in a cluster setting

Since they rely on println to display results, we need to first collect those results to the driver to have them actually display locally.

This issue came up on the mailing lists [here](http://mail-archives.apache.org/mod_mbox/incubator-spark-user/201311.mbox/%3C2013111909591557147628%40ict.ac.cn%3E).