#2532: If Shotwell can't create vital data files/directories at startup, instead of logging an error and exiting, it displays a dialog box error and exits.  NOTE: This introduces new translatable strings that are not the .pot file.  Although past string freeze, we feel these are very rare cases and won't be seen by 99.9% of users, but should be visible to that one-tenth of a percent that have done something really odd with their permissions.