Fix for broken forums due to forum entry with no start_date

modification of @jrbl's version to handle a dict with value None
moving segment io setting below auth.json
change form of making datetime.max aware (in UTC)
Merge pull request #175 from edx/fix/jbau/handle-None-discussion-start_time

Fix for broken forums due to forum entry with no start_date
Update CHANGELOG.rst
Fix merge conflict in CHANGELOG.rst.