Initial commit
Started development of Neurons
Added initial constructors to Neuron
Added getters and setters of _inputs
Corrected some methods.

Now removeInput, removeInputAtIndex and addInput will modify
_inputChange too.
Added a new getter for inputs: inputsSize
Added getters and setters of InputChange
Added getters and setters of bias
Added getters and setters of _delta
Added Tests
Completed basic operations with Neuron
Corrected Constructors
Corrected AddInputTest
Corrected addInput method
Added getOuput Test
Writed getOuput method
Writed getOutput test
Added a method to clone a Neuron and a method to clear Neuron's inputs
Corrected clone method
Added equals method