Bug 1026474 - [dolphin][Contacts]No Error pop up when exporting contacts to SD card, while SD card is full. r=jmcf

Unfortunately that value comes from the shared function `getStorageIfAvailable`, living in shared I don't want to update this function (created by the media team).

Probably cause of the fact that one could be the error to get the storage (string), and the second once we have the storage but we dont have space (that is this bug)