Added bob.bio.gmm to requirements (to have in on Travis)

requirements.txt

@@ -18,7 +18,8 @@ bob.db.base
 bob.db.verification.utils 
 bob.db.verification.filelist
 bob.db.atnt  # required for testing
-bob.bio.base 
+bob.bio.base
+bob.bio.gmm
 bob.learn.boosting 
 bob.ip.facedetect
 bob.ip.flandmark