rose suite-log-view/suite-hook: use cylc-suite.db

This addresses #471 and #22.
* Rotation of the suite log will no longer be a problem.
* It will now get the actual remote job's `user@host`
  (instead of having to re-run `rose host-select` which may return something different).
* `cylc get-config` will now only be used by `rose suite-run`
  and the `fcm_make` built-in application.

N.B. 2 current functionalities will not work correctly at the moment
as `cylc-suite.db` does not appear to have the following information:
* The signal of a job killed by a signal.
* The exit time of a failed job that can be retried.