Improvements:
_Renamed the project file, "analyticsLogsWriter" class, test class and
"toString" method
_Remove the numeric key format from keyPair class and AnalyticsFormatter
class
_Created a constructor with a category parameter
_Synchronized some methods in order to convert the code in thread safe
_Added the timestamp attribute when it is ready to write the results
_Del operation coded
_Test created:
   Constructor test
   KeyTest
   Del test
   KeyPar Tests