Option 1 of 2: Convert spark-parent module name to spark-parent_2.10 / spark-parent_2.11

Author: Sean Owen <sowen@cloudera.com>

Closes #4912 from srowen/SPARK-6182.1 and squashes the following commits:

eff60de [Sean Owen] Convert spark-parent module name to spark-parent_2.10 / spark-parent_2.11