challenge 01-01-01-experiment-methods (finished)

! modify #get_rid_of_surrounding_whitespaces to return a whitespace
  stripped copy of string
! modify #belongs_to? to return boolean if a string contains a word
! modify #replace to return a string with new characters replacing
  old ones
! modify #exactly_divide to return non-euclidean (floating
  point-based) division result from an operand by a a_divider
! modify #divisible_by_two to return boolean if number is even
! modify #random_subset to return a random subset of a sample array
  as long as given sample_size
! modify #randomize to return a randomized copy of an array
! modify #ascending_order to return an (ascending order) sorted copy
  of an array