Merge pull request #2 from danwhitfield/master

Adding worksheets which shows factorial and scalacheck
exercise 5.2.1
first failing scalacheck test. my code is wrong but I'm soo happy
Merge branch 'master' of https://github.com/grahaminn/ScalaByExample
move Sum.scala
exercise 5.2.2
remove unnecessary target contents
Merge branch 'master' of https://github.com/grahaminn/ScalaByExample