Upgrades (work in progress)

fixes #100
adds AdaptiveLearningRate Observer
refactored Minima from EarlyStopper (so it can be used without early-stopping)

Still need to:
 [ ] integrate AdaptiveLearningRate to recurrentlanguagemodel.lua
 [ ] write RecurrentDictionary doc
 [ ] write Minima doc
 [ ] write AdaptiveLearningRate doc