If is not initialized, the check for the espeak plugin will fail.
This patch also check for the espeak plugin at the beginnig
avoiding check every time the function enabled() is called.
Now when the espeak plugin is not installed there will be an
error (logging.error) in the log. Instead of the ugly message
of Gst
Also, if Gst isnt installed it debug a error too.
Fixes#3345
To display a list of translated language names in the UI,
we add a list of the available languages, because the espeak
language names are not translated.
