Synced translations with Transifex

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Prepared release and bumped version numbers to 1.8.4.0

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Fix libgit2 clone failure when specifying branch name

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
Drop unneeded translation string

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>