rose suite-run --reload: fix None concatenation.
rose suite-run: fix reload logic.

* Run "cylc reload --force" to prevent interactive prompt.
* Fix log-keep logic due to incorrect symlinks created by previously
  incorrect reload.
* Fix location of previous suite engine configuration in reload mode.
Revert "rose suite-run --reload: fix None concatenation."

This reverts commit 2549071b5766c362933c21c9b977c30a80bfe4d9.
Merge pull request #429 from matthewrmshin/rose-suite-run-reload.fix

rose suite-run --reload: fix logic
Merge branch 'master' into 54.suite-run.validate.strict
Minor logic improvement and comment fix.