rose-bush.js: fix format string and int rounding

1. Correct format string for seconds in a minute.
2. Use `Math.floor` instead of `Math.round`.
Merge pull request #1065 from matthewrmshin/fix-rose-bush-js

rose-bush.js: fix format string and int rounding
rose bush: recognise the `ready` status

This change is in anticipation of cylc/cylc#794.
Merge pull request #1068 from matthewrmshin/submitting-to-ready

rose bush: recognise the `ready` status