Update fr.json

translation into french of
i18n-bitmessage-desc
i18n-mediacrush-desc
i18n-mediacrush-self-desc
i18n-centos-desc
i18n-smeserver-desc
i18n-yunohost-desc
i18n-server-software
i18n-server-os-title
Update fr.json

Little mistaping: Serveur instead of Server
Merge pull request #509 from juanito003/patch-1

Patch 1