LP1893463: Prevent duplicated report outputs

LP1893463: Prevent duplicated report outputs

When re-running recurring reports that are interrupted,
it's possible to end up with a duplicate copy of the next
recurrance of that report. This branch adds a unique index
to reporter.schedule and tells clark-kent.pl not to worry
about it.

For the purposes of this change a duplicate report is
one where report.schedule has identical values for report,
(output) folder, runner, run_time, and email.

Signed-off-by: Jason Boyer <JBoyer@equinoxinitiative.org>