Add original_id column + logic. db -> v301

Adds an original_id to the Events table for local reference to
an original event for exceptions. It also adds logic to keep this
value in sync with the original_sync_id so apps don't have to
update for it to continue working.

Change-Id: I0034ecedb6f7b582ba823daab8656b7778781d84
3 files changed