Update face_recognition.lua

[Huipie1]

Add support for running the face recognition from docker, this is usefull if you don't want the hassle to install the additional software but have docker available.

python(without docker) and docker-gpu have not been tested but should work if you have the right prerequisites

[wpferguson]

If I understand correctly you only tested the docker-cpu branch and none of the others?

[Huipie1]

Exactly, I only tested it with the cpu docker branch, as I don't have those available currently (also the reason why I added support for docker).

-edited the opening post to clarify a bit more