Deprecate floating pipelines

[jbodah]

With mix format now being a thing we can simplify a lot of our indent code. For example, floating pipelines were previously a bit of a hassle

       [h | t] =
         "a,b,c,d"
         |> String.split(",")
         |> Enum.reverse()

instead of

       [ h | t ] = "a,b,c,d"
                   |> String.split(",")
                   |> Enum.reverse

[jbodah]

cc: #434

[jbodah]

Closing - I don't care how we handle stuff outside of "mix format"