Re-word instructions for class2 exercise 3
Remove class4 git_config
Fix exercise name
Tweak branching example
Improve class4 exercises
Tweak TIP
Merge branch 'master' of https://github.com/codefellows/sea-c21-ruby

Conflicts:
	lib/class3/exercise2.rb
	lib/class3/exercise4.rb
	lib/class4/exercise2.rb
just fixing things that didnt merge