Fixing white screen of death when tour ids are not in TapConfig.plist

I came through the problem which faced hannolans here : 
http://bit.ly/12H8BaL
There comes a quick fix. I've added a default config for tours in TapConfig.plist : if the tour is not referenced inside this plist, it no more crashes you with a white screen of death.

Content of commit :
TourTabBarViewController : adding & using a default config for tours in TapConfig.plist which is used when no custom tour config (referenced by id) is available inside TapConfig.plist