Add stub solutions for all exercises

[NobbZ]

There should be a stub solution for every exercise, roughly like the following:

-module($module_name).

-export([fun_a/0, fun_b/2]).

fun_a() -> undefined.

fun_b(Param1, Param2) -> undefined.

test_version -> 1. % or whatever version is needed to pass the tests

Also we need a check in bin/journey-test that fails if it is missing.

if [[ ! -f "${exercism_exercises_dir}/erlang/${exercise}/src/${module}.erl ]]; then exit 1; fi

Should be a sufficient test, best put between current lines 201 (introduction of $module) and 202 (overwriting any stub that might exist with the example solution).

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[JordanAdams]

I've put a PR to resolve this here: #177