Remove class AdaptiveLearningRateScheduler

[FFMG]

The class AdaptiveLearningRateScheduler is not working properly and does not really follow any common standards.

Now that we have learning rate boost and decay this class is no longer needed.

We must also remove

• The option that makes use of it.
• The serializer that might save it.
• The log message when NN training is starting.