Add default_config, and cfg[:timeout] for tasks

- Using the @default_config attribute in a module will fill out a default
value.
- cfg[:timeout] sets the timeout for the task for this module to finish.
- Update Omnibot.Irc.route_msg/2 to have each task spawn a second task,
  while the first task waits for its child to finish, otherwise killing
  it.

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

lib/contrib/linkbot.ex

@@ -2,6 +2,8 @@ defmodule Omnibot.Contrib.Linkbot do
   use Omnibot.Module
   require Logger
 
+  @default_config timeout: 30_000
+
   defmodule Client do
     use Tesla
 
@@ -13,6 +15,7 @@ defmodule Omnibot.Contrib.Linkbot do
 
     def get_title(url) do
       if should_get?(url) do
+        Process.sleep(11_000)
         resp = get!(url)
         %{"title" => title} = Regex.named_captures(@title_regex, resp.body)
         title