add exercises_spec.rb
add ex1 and test
add ex4 and commit
add ex5 and test
add ex6 and test
add ex7 and test
add ex 8 and test
add ex9 and test
add exercise 10 and test
add ex11 and test
add ex12 and test
Merge branch 'spec-writing' of github.com:MelizzaP/spec-writing into spec-writing