Merge pull request #3 from rbenaley/master

guard fix: two successive 'when' means boolean 'OR' not 'AND'
Ignore .DS_Store
Exercises about processes
Number guessing game server
improvements to the guess number game
a stub file for the client
guess number moved to meetup 3
flush.exs and counter are swapped in order (everyone said flush.exs has to come first)
Slides for the second meetup
Merge branch 'master' of github.com:belgian-elixir-study-group/meetup-materials
Update flush.exs
Update counter.exs
presentation #1
copy paste  materials for meetup 3
Exercism assignments
added Devspace Anagram Webserver
exercises on macros
tests commented off
Slides for the “Exploring ExUnit” sessions