[plugin] remove superfluous parens in is_installed()

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>
[plugin] fix whitespace in Plugin._copy_symlink()

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>
[plugin] remove superfluous parens in Plugin._do_copy_path()

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>
[plugin] remove superfluous parens in Plugin.check_ext_prog()

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>
[plugin] remove superfluous parens in Plugin.get_cmd_output_now()

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>
[plugin] fix indentation in Plugin._collect_copy_specs()

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>
[plugin] remove superfluous parens in Plugin.report()

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>
[plugin] remove unused itertools import

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>
[plugin] ensure Plugin has an 'archive' member

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>