exercise implementation
Merge remote-tracking branch 'upstream/master'

Conflicts:
	src/main/scala/Duplicates.scala
	src/test/scala/DuplicatesTest.scala
adjust the songId type from String to Long.
Added pending tests & adjusted songId type to Long.
adjust duplicateSongsWithCount function . Some test refactor
refactor on tests definition
adjust assert method expresion
'Solution' trait created to hold data of the final solution
'Solution' trait created to hold data of the final solution
Merge remote-tracking branch 'upstream/master'

Conflicts:
	src/test/scala/DuplicatesTest.scala
	src/test/scala/util/Solutions.scala
Merge branch 'master' into gpolito-impl

Conflicts:
	src/main/scala/Duplicates.scala
	src/test/scala/DuplicatesTest.scala
	src/test/scala/util/Solutions.scala