Enforce Maven 3.3.3+ in the build. (Also update the scala compiler plugin while we're at it.)

Author: Sean Owen <sowen@cloudera.com>

Closes #7852 from srowen/SPARK-9521 and squashes the following commits:

3093039 [Sean Owen] Enforce Maven 3.3.3+ in the build. (Also update the scala compiler plugin while we're at it.)