Fix up change-yaml.sh to generate md5 sum for spark

[tmckayus]

This is transitional while we wait for sha512 support in cekit.

[todo]

remove this download when sha512 support lands in upstream cekit (tmckay)

oshinko-s2i/change-yaml.sh

Lines 73 to 78 in 9deb637

	# TODO remove this download when sha512 support lands in upstream cekit (tmckay)
	# Since this is big let's see if it's already there
	if [ -f "/tmp/spark-${SPARK}-bin-hadoop${HVER}.tgz" ]; then
	echo
	echo Using existing "/tmp/spark-${SPARK}-bin-hadoop${HVER}.tgz", if this is not what you want delete it and run again
	echo

---

This comment was generated by todo based on a TODO comment in 9deb637 in #281. cc @tmckayus.

[todo]

remove this checksum calculation when sha512 support lands in upstream cekit (tmckay)

oshinko-s2i/change-yaml.sh

Lines 93 to 98 in 9deb637

	# TODO remove this checksum calculation when sha512 support lands in upstream cekit (tmckay)
	calcsum=$(sha512sum /tmp/spark-${SPARK}-bin-hadoop${HVER}.tgz | cut -d" " -f1)
	sum=$(cat /tmp/spark-${SPARK}-bin-hadoop${HVER}.tgz.sha512 | tr -d [:space:] | cut -d: -f2 | tr [:upper:] [:lower:])
	if [ "$calcsum" != "$sum" ]; then
	echo "Failed to confirm authenticity of Spark archive, checksum mismatch"
	echo "sha512sum : ${calcsum}"

---

This comment was generated by todo based on a TODO comment in 9deb637 in #281. cc @tmckayus.

[todo]

replace this with sha512 when it lands in upstream cekit (tmckay)

oshinko-s2i/change-yaml.sh

Lines 113 to 118 in 9deb637

	# TODO replace this with sha512 when it lands in upstream cekit (tmckay)
	calcsum=$(md5sum /tmp/spark-${SPARK}-bin-hadoop${HVER}.tgz | cut -d" " -f1)
	$SED -i '\@url: https://archive.apache.org/dist/spark/@!b;n;s/md5.*/md5: '$calcsum'/' image.*.yaml
	#change the spark version in the env var
	$SED -i '\@name: SPARK_VERSION@!b;n;s/value:.*/value: '$SPARK'/' image.java.yaml

---

This comment was generated by todo based on a TODO comment in 9deb637 in #281. cc @tmckayus.

[tmckayus]

@elmiko ptal
This is part of the in-flight spark 2.4 update

[elmiko]

this looks good, i think my change has gone into upstream cekit for the sha512 stuff. maybe we should confirm it in our build pipeline?

[tmckayus]

is that part of cekit 3? if so we need to modify the image.yamls, we can do that all at once

[elmiko]

looks like my changes are in cekit 3.1 for sure, so maybe we should just proceed as is and leave the todos for later.

[tmckayus]

Merging before tests complete, this is just a utility script