Applied changes acording to code review in the AlgorithmNorvig class

* Updated the AlgorithmNorvig class according to code review
	* Added comments according to PEP 257
	* Renamed some variables in order to have variable more understandable

* Added the AlgorithmBase Strategy interface
	* Added the AlgorithmSolver context
	* Added the AlgorithmNorving class
	* Added the unittest for the AlgorithmNorvig solver method