Add solution for APS Captcha

[dsuess]

Here is another take on the APS Captcha problem using random forests: Instead of training the classifiers on the pixel values directly, I use parts of a previously trained CNN classifier as a feature extractor (see the last two cells).

P.S Of course, in practice one would use a pre-trained general pupose feature extractor.

[peterwittek]

Wow, this is pretty awesome. Thanks for the solution.