Added CodeCorps.GitHub.Event.Handler behaviour

Author: begedin

lib/code_corps/github/event/handler.ex

@@ -0,0 +1,16 @@
+defmodule CodeCorps.GitHub.Event.Handler do
+  @moduledoc ~S"""
+  Default behavior for all GitHub webhook event handlers.
+  """
+
+  alias CodeCorps.GithubEvent
+
+  @doc ~S"""
+  The only entry point a GitHub webhook event handler function should contain.
+
+  Receives a `CodeCorps.GithubEvent` record and a payload, returns an `:ok`
+  tuple if the process was successful, or an `:error` tuple, where the second
+  element is an atom, if it failed.
+  """
+  @callback handle(GithubEvent.t, map) :: {:ok, any} | {:error, atom}
+end