(I wasn't sure how to automatically set `SPARK_YARN=true` and `SPARK_HIVE=true` when running scalastyle, but these are the errors that turn up.)

Author: Sean Owen <sowen@cloudera.com>

Closes #413 from srowen/SPARK-1497 and squashes the following commits:

f0c9318 [Sean Owen] Fix more scalastyle warnings in yarn
80bf4c3 [Sean Owen] Add YARN alpha / YARN profile to scalastyle check
026319c [Sean Owen] Fix scalastyle warnings in YARN, Hive code