Use relative import of upload in data_ingestion

py3 nosetests fails on 'import upload' in the
data_ingestion script, causing a travis build breakage.

Two other scripts use 'import upload'
- flickrripper
- imagetransfer

And other use 'import <script>' syntax, which will
also fail on py3 nosetests when we have tests for
them.

This change only updates data_ingestion to use
the 'from scripts import upload' import style, to fix
the build breakage while waiting on feedback from nosetests
https://github.com/nose-devs/nose/issues/839

Also update data_ingestion tests to use the new test metaclass.

Change-Id: If40087657718749dd54a37834d551f97424b4914