Several features

In this MR I'm adding several features.

I know that we should have one MR per feature, but I simply couldn't breakdown my work on different MR. It would take a lot of my time. Sorry in advance for that.

So, in this MR I'm adding the following features:

• Created pytorch database interfaces for WebFace42M, Mobio, MSCeleb, Morph, MEDS, RFW (the last 5 contains demographic information)
• Added 2 annotators. The FaceXZoo face detector and face landmark detector (it contains 106 landmarks).
• Created a bob database for the VGG2 Database (it contains demographic information (gender and race labels)).
• Added some pytorch building blocks