Update the welcome email.
Add getting started gif

To add a gif.
First convert from a .mov video:
ffmpeg -i  screen.mov -r 10 -f image2pipe -vcodec ppm - | convert -verbose +dither -layers Optimize -resize 560x560\> - gif:- | gifsicle --colors 128 --delay=1 --loop --optimize=3 --multifile ->  getting_started.gif

Signed-off-by: Maxime Gaillard <maxime@naeka.fr>
Small fixes and updates on email texts

Signed-off-by: Maxime Gaillard <maxime@naeka.fr>
Add translation in french on emails

Signed-off-by: Maxime Gaillard <maxime@naeka.fr>