[SPARK-6673] spark-shell.cmd can't start in Windows even when spark was built

added equivalent script to load-spark-env.sh

Author: Masayoshi TSUZUKI <tsudukim@oss.nttdata.co.jp>

Closes #5328 from tsudukim/feature/SPARK-6673 and squashes the following commits:

aaefb19 [Masayoshi TSUZUKI] removed dust.
be3405e [Masayoshi TSUZUKI] [SPARK-6673] spark-shell.cmd can't start in Windows even when spark was built