Reset started and finished times on new submission.
Fixed "cylc list -c START[,STOP]".

Was using an obsolete function arg for old-style cold-start tasks.
Added tests for cylc-list command.
Merge pull request #1231 from arjclark/cylc_gui.clear_old_timings

cylc gui (task proxy): Reset started and finished times on new submission.
Merge pull request #1232 from hjoliver/list-cmd.fix-cycle-opt

Fix the list command cycle option