Allow to specify time scale locale

[cghislai]

Currently, the time scale uses the default moment locale.
Calling moment.locale(locale) does not seems to help.
There should be a way to specify the locale in the time scale settings, or at the chart options level.

[etimberg]

@cghislai setting the moment global locale should work if done before the chart is drawn. If the chart is already drawn, update() needs to be called

[cghislai]

Yep, sorry, used a wrong locale object :/ moment could have told me it was incorrect..