Ruby challenges 2, 4, 30, 37, 39, 40, 93

 new file:   Ruby/challenge2.rb - Longest Lines
 new file:   Ruby/challenge4.rb - Sum of Primes
 new file:   Ruby/challenge30.rb - Set Intersection
 new file:   Ruby/challenge37.rb - Pangrams
 new file:   Ruby/challenge39.rb - Happy Numbers
 new file:   Ruby/challenge40.rb - Self Describing Numbers
 new file:   Ruby/challenge93.rb - Capitalize Words