FR translation + ESOPE improvements

Hi,

I've updated your nice plugin with some changes that better fit our needs, here are the changes details : 
- languages/en.php : only spacing +  new string
- languages/fr.php : added
- views/default/plugins/rssimport/settings.php : added 2 settings 
   1. Imported element container setting : defaults to the container, instead of the owner, so to the group in a group, and the user when used outside of a group
   2. Enable per-tool import setting : gives a finer control over import availability
   Also there was another option (in a previous backport to 1.6) that let the tool be restricted to user/admins and also groupadmin - which is not enabled in this PR (as there is already a user/admin setting)
- lib/functions.php : new functions that implement the added settings, and also adds a filtering function based on imported domain name + real source URL detection. And also use a translation string for date.

If you are interested into these changes, we can discuss it further so i can update it until it's OK for you to merge ?
I could make a few more changes such as changing the defaults so it better integrates with existing instances, implement the group admin setting (which i think gives much more flexibility for big networks), and add a hook in the filtering function so it becomes more extendable...

Please let me know if you are interested.

Best regards,
Florian DANIEL