Badges, poll and french Translation

New Badges system
New string in the poll plugin + change the term "poll option"
Re-add some empty strings (like notifications.title)
And updates
Poll - Topic Term

Use topic instead of thread to keep the same term for the user.
Add s3_backup_config_warning

Note that only one of the two warnings can be shown, because they are checked in the same method.
Dutch translation updated
Dutch translation updated
Merge pull request #2142 from sanderdatema/patch-5

Dutch translation updated
Merge pull request #2135 from Onaldanm/poll-badge-fr

Translation: Badges, poll and french updates
Merge pull request #2134 from Onaldanm/patch-1

Poll - Topic Term
Minor fix for location of osx_dev script
Merge pull request #2143 from czarneckid/patch-1

Minor fix for location of osx_dev script
Merge pull request #2139 from riking/s3-backup-warning

Add s3_backup_config_warning
Add excerpt column to topics table to remove N+1 query in ListableTopicSerializer
Remove another N+1 query from categories page
Better error messages if the "Send Test Email" button fails.
Ability to customize the logo in digest emails
BUGFIX: dupe topic names could booby trap seeding
Stop leaking site_email in rss
BUGFIX: stabilize the buttons in revision history UI
BUGFIX: BackupChunksMerger

- actually remove the tmp directory
- merge all the chunks into a .tmp archive and then remove the .tmp extension once done
BUGFIX: don't alery myself when I link to myself