Externalize some string

+ Externalize some string
+ Add french translation for theme
Update strings.xml

clear_finished_transferts => clear_finished_transfers
Update strings.xml

clear_finished_transferts => clear_finished_transfers
Update transfers.xml

clear_finished_transferts => clear_finished_transfers
Merge pull request #18 from DoubleYo/master

Extract some hardcoded strings and add French translations