fix for StorageList and tests added

gluon/storage.py
StorageList had a recursion error (please check the implementation before committing)

gluon/tests*
added the fix_path module to avoid those ugly lines at the beginning of each test file
added tests for gluon.contenttype and test_fileutils
added tests for missing Storage methods

gluon/storage.py

@@ -151,10 +151,10 @@ class StorageList(Storage):
 
     def __getattr__(self, key):
         if key in self:
-            return getattr(self, key)
+            return self.get(key)
         else:
             r = []
-            setattr(self, key, r)
+            self[key] = r
             return r