No local return dialyzer issue

[larshesel]

If I have Rambo.run("echo") in my code, dialyzer will complain with a no local return error.

This seems to be because Rambo.run/1 calls Rambo.run/3 with the second argument set to nil (https://github.com/jayjun/rambo/blob/master/lib/rambo.ex#L66) which violates the args() type of Rambo.run/3 (https://github.com/jayjun/rambo/blob/master/lib/rambo.ex#L14).

[jayjun]

Thanks for the helpful investigation! Fixed in 0.3.3.