Set launched_at at start of action if not set in DB

This is just in-case the action goes past the audit period. It is also
    important to make sure we are not overwriting launched_at if it is
    already set because the end event could have already been recieved.
Merge pull request #75 from ramielrowe/pre_action_launched_at

Set launched_at at start of action if not set in DB