WIP: Resolve "Some database interfaces do not provide access to the annotations stored in the low-level databases"

Closes #14 (closed)

Added a new intermediate biofile and biodatabase interface that stores the low_level file and database objects, and use the annotations function from the low-level database to request the annotations.

I have modified the test cases such that they actually require the annotations to be non-None if the low-level database has internal annotations. These tests will fail unless the database is correctly implemented.

@amohammadi @tiago.pereira @andre.anjos Do you think this is a reasonable way to proceed?

bob/bio/face/database/__init__.py

 #!/usr/bin/env python
 # vim: set fileencoding=utf-8 :
 
-from .database import FaceBioFile
+from .database import FaceBioFile, FaceBioFileWithAnnotations, FaceBioDatabaseWithAnnotations
 from .mobio import MobioBioDatabase
 from .replay import ReplayBioDatabase
 from .atnt import AtntBioDatabase
@@ -33,6 +33,8 @@ def __appropriate__(*args):
 
 __appropriate__(
     FaceBioFile,
+    FaceBioFileWithAnnotations,
+    FaceBioDatabaseWithAnnotations,
     MobioBioDatabase,
     ReplayBioDatabase,
     AtntBioDatabase,