implemented reverseString function
Merge branch 'reverse_string'

* reverse_string:
  implemented reverseString function
adding interface for filterWordLength function
adding initial implementation of the function
added test output and fixed open header
Merge branch 'filter_text_array'

* filter_text_array:
  added test output and fixed open header
  adding initial implementation of the function
  adding interface for filterWordLength function
adding dateGreeting interface
added implementation for dateGreeting plus tests
Merge branch 'date_greeting'

* date_greeting:
  added implementation for dateGreeting plus tests
  adding dateGreeting interface