[BUGFIX] Wrong alignment of French labels for login screen

Since the username label changed from "Utilisateur" to "Nom d'utilisateur"
in French, the alignment of labels and text fields is broken.

Change-Id: I35f28fd61f8c4a3e133949ae8eb865af0e0a1bc9
Fixes: #30688
Releases: 4.5,4.6
Reviewed-on: http://review.typo3.org/5648
Reviewed-by: Eric Chavaillaz
Tested-by: Eric Chavaillaz
Reviewed-by: Steffen Gebert
Tested-by: Steffen Gebert
Reviewed-by: Xavier Perseguers
Tested-by: Xavier Perseguers