Don't crash if there is no quota set for a folder.
Don't crash if there is no quota set for a folder.

svn path=/trunk/KDE/kdepim/; revision=780651

lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi