use 0.13 exunit exception in doctest
use 0.13 exunit exception in doctest

michalmuskala/elixir,pedrosnk/elixir,lexmag/elixir,antipax/elixir,elixir-lang/elixir,kelvinst/elixir,antipax/elixir,ggcampinho/elixir,gfvcastro/elixir,lexmag/elixir,kelvinst/elixir,kimshrier/elixir,ggcampinho/elixir,gfvcastro/elixir,pedrosnk/elixir,beedub/elixir,beedub/elixir,kimshrier/elixir,joshprice/elixir