Does anyone know a good tutorial on reinforcement learning that describes a practical application like this?
Follow this to retrain the Inception network: https://www.tensorflow.org/tutorials/image_retraining
Follow this to run an image through your model for classification: https://www.tensorflow.org/tutorials/image_recognition
I will probably publish in some time (when I'm not so busy doing other projects) some code samples too but until that I can give you tips.
You should start inspecting how the pre trained models (Inception v3/v4) works, what kind of layers they have and then decide what layers you want to use and what not. In case of Tensorflow, the tensorboard is very good tool for inspecting the model inner layers.
If you want to get started even more easier you should probably take a look into Tensorflow Slim models (https://github.com/tensorflow/models/tree/master/slim)
There is quite beginner friendly instructions for simple fine tuning of the models and it should take you pretty far.