replace the original_directory path in the low-level db too

Since some low-level dbs (most of them) accept original_directory and annotation_directory, it is best to replace the paths there too. Here I am assuming that the low-level db exists in BioDatabase._db and have made sure this is the case for all high-level databases. This may not be the solution so I am open to suggestions.

bob/bio/base/database/database.py

@@ -195,8 +195,17 @@ class BioDatabase(six.with_metaclass(abc.ABCMeta, bob.db.base.Database)):
             self.original_directory = replacements[self.original_directory]
 
         try:
+            self._db.original_directory = self.original_directory
+        except AttributeError:
+            pass
+
+        try:
             if self.annotation_directory in replacements:
                 self.annotation_directory = replacements[self.annotation_directory]
+                try:
+                    self._db.annotation_directory = self.annotation_directory
+                except AttributeError:
+                    pass
         except AttributeError:
             pass