rose suite-run: fix hang if prev cylc gui open

If `cylc gui` launched by the previous `rose suite-run` is still open,
the `rose suite-run` command fails, and any subsequent invocation hangs.
This change fixes 2 problems:
1. `log/rose-suite-run.log` is still considered opened by `cylc gui`.
   (It looks like the process has inherited the file handle, even though
   it is launched by `nohup`). When the new `rose suite-run` tries to
   remove the log directory, it is unable to do so. This change closes
   the file before launching `cylc gui`.
2. Problem 1 creates a `log-DATETIME.tar.gz` file, but left
   `log-DATETIME/`. On subsequent invocation of `rose suite-run`, the
   `gzip` command hangs, waiting for an overwrite confirmation. This
   change calls `gzip` with `-f` to force an overwrite.
Merge pull request #1080 from matthewrmshin/fix-suite-run-hang-if-cylc-gui-open

rose suite-run: fix hang if prev cylc gui open