[Localization] log-activity french translation

[s.boutayeb at free.fr]

Hi Bastien, Simon,

I think FR: journal is the adequate translation of EN: log, in our context.
However, Simon made a good point with the possible confusion between the
activities. Consequently, your proposition (FR: journaux) is a possible and
valuable one.
The other variant (FR: log) is a jargon-term and should generally be avoided in
a device like the XO, considering the intended public of the XO. However, the
argument in favor of "log" is that the intended users of the log-activity don't
are supposed to be the kids. I have updated to "log", but still remain open to
the discussion.

Bests

Samy