Update gensupport.rb

Hopefully fixing: undefined method `collect' for #<String:0x007ff92c24c2c8> (NoMethodError) in Ruby 1.9.3
Update gensupport.rb

Updating usage of String for > Ruby 1.9.3
Merge pull request #12 from aadlww/patch-1

Error: undefined method `collect' for #<String:0x007ff92c24c2c8> (NoMethodError) in Ruby 1.9.3