Backend trainer/model initialization

[skywolf829]

The frontend will click a button and attempt to initialize a trainer/model on the backend (see #4). The message from the frontend will include all the hyperparameters needed in the Settings object.

Requirements

• Update the settings object, initialize the model, then initialize the trainer. No training should start, but it should be ready to be started immediately.
• After (trying) to initialize the model and trainer return a message to the frontend: -- Upon success, return error code 0 and a string with some message like "Model initialized" etc -- Upon failure, return some nonzero error code and a message with the issue.

[skywolf829]

Initialization is started when a message from the frontend is received. Error checking is handled. All parameters are updated properly.

The dataset is initialized in a thread since it is an IO operation that can take a while (up to 2 minutes on my laptop) to load the dataset and process it.