Update and rename dice.rb to lib/dice.rb

* initialize is a private method
* modified code to make it simpler
* You do not need the ()s while declaring a method unless it has parameters
* moved file into a library folder
Update and rename score_sheet.rb to lib/score_sheet.rb

* simplified code
* added documentation
* Removed extra ()s
* renamed Score_Sheet to ScoreSheet
* Added multiline comments
Merge pull request #1 from Zrp200/master

Mass simplified code