Docs: convert to ISO 8601

A first attempt.
Docs: remove cold start references

And other improvements.
First draft of a solution for #1375
Use isodatetime-2014.08.0-4-ged54df8
Fix tutorial suite syntax

Was missing `graph=`.
tutorial doc: update `rose date` offset syntax
Tutorial docs: fix duration syntax
Fix example suite syntax spacing
Tutorial doc: ISO 8601 clock-triggered syntax
Doc: update for cylc 6

Fix directory path for `work/`.
Remove unnecessary comments.
rose documentation: fixes/enhancements for suite tutorials
Merge pull request #1374 from matthewrmshin/doc-iso8601

 Docs: convert to ISO 8601
rose bush jobs: fix status for retried jobs

A failed job to be retried should be marked failed.
Merge pull request #1378 from matthewrmshin/fix-rose-bush-jobs-retry

rose bush jobs: fix status for retried jobs
Cylc -> cylc
Merge pull request #1376 from matthewrmshin/isodatetime-2014.08.0-4-ged54df8

Use isodatetime-2014.08.0-4-ged54df8
address feedback
Merge pull request #1377 from benfitzpatrick/doc.tweaks

rose documentation: fixes/enhancements for suite tutorials
Update CHANGES.md
Update CHANGES.md