Improvement of French translations

Signed-off-by: Balthazar Rouberol <balthazar.rouberol@mapado.com>
New strings translate to CS
Merge pull request #338 from brouberol/master

Improvement of French translation
Fix XML errors in Czech translation
Merge pull request #339

Update Czech translation
Fix Spanish translation

Information provided by Luis Angel Yague on Google+
Add an index for a heavy query
Merge branch 'master' of git://github.com/k9mail/k-9

Conflicts:
	src/com/fsck/k9/mail/store/LocalStore.java