Refresh the plugin to the current scribes.

* fix `setup.py` to actually install plugin in the proper place
  (`~/.config/scribes/LanguagePlugins`)
* change activation shortcuts to `<ctrl><alt>j` and `<alt><shift>r` which
  are not conflicting with the default scribes shortcuts.
* remove trailing spaces

Signed-off-by: Matěj Cepl <mcepl@redhat.com>