Add background_task example to showcase background tasks.

examples/background_task.py

@@ -0,0 +1,32 @@
+import discord
+import asyncio
+
+client = discord.Client()
+
+@asyncio.coroutine
+def my_background_task():
+    yield from client.wait_until_ready()
+    counter = 0
+    channel = discord.Object(id='channel_id_here')
+    while not client.is_closed:
+        counter += 1
+        yield from client.send_message(channel, counter)
+        yield from asyncio.sleep(60) # task runs every 60 seconds
+
+@client.async_event
+def on_ready():
+    print('Logged in as')
+    print(client.user.name)
+    print(client.user.id)
+    print('------')
+
+loop = asyncio.get_event_loop()
+
+try:
+    loop.create_task(my_background_task())
+    loop.run_until_complete(client.login('email', 'password'))
+    loop.run_until_complete(client.connect())
+except Exception:
+    loop.run_until_complete(client.close())
+finally:
+    loop.close()