Modify paycheck to print out hashes in base64.

Both the update engine and sha256_partitions.sh print out hashes in
base64 encoding. Let's stay consistent with ourselves so we can diagnose
hash mismatches correctly.

BUG=None
TEST=Ran it with a delta payload and compared hashes with sha256_partitions.sh
and logs from applying it in the update_engine.

Change-Id: I90c511b936792a073fbe069065ff53c24f47041c
Reviewed-on: https://gerrit.chromium.org/gerrit/46910
Commit-Queue: Chris Sosa <sosa@chromium.org>
Reviewed-by: Chris Sosa <sosa@chromium.org>
Tested-by: Chris Sosa <sosa@chromium.org>
1 file changed