renamed failed_jobs original_id

The name conflicts with switchman's aliasing of the un-shareded id
method to original_id. This adds a new column original_job_id and copies
the old column over to it. A subsequent commit will drop the old column.

refs CNVS-12828

test plan: after running migrations, verify that the original job id
shows up for failed jobs in the jobs ui. This won't fix failed jobs that
were recorded in rails3 before this fix, those original ids have been
lost. New jobs that fail in rails3 will now record the original id
properly, though.

Change-Id: Ie974bf3fc932bcef7f09315ca5314e3bdcc6b680
Reviewed-on: https://gerrit.instructure.com/34358
Reviewed-by: Cody Cutrer <cody@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: August Thornton <august@instructure.com>
Product-Review: Brian Palmer <brianp@instructure.com>