[V3 Core] add update check (#1388)

* [V3 Core] add update check

* [V3 Core] have it DM the owner if out of date

redbot/core/events.py

@@ -2,6 +2,9 @@ import sys
 import codecs
 import datetime
 import logging
+from distutils.version import StrictVersion
+
+import aiohttp
 import pkg_resources
 import traceback
 from pkg_resources import DistributionNotFound
@@ -106,6 +109,24 @@ def init_events(bot, cli_flags):
 
         INFO.append('{} cogs with {} commands'.format(len(bot.cogs), len(bot.commands)))
 
+        async with aiohttp.ClientSession() as session:
+            async with session.get("http://pypi.python.org/pypi/red-discordbot/json") as r:
+                data = await r.json()
+        if StrictVersion(data["info"]["version"]) > StrictVersion(red_version):
+            INFO.append(
+                "Outdated version! {} is available "
+                "but you're using {}".format(data["info"]["version"], red_version)
+            )
+            owner = discord.utils.get(bot.get_all_members(), id=bot.owner_id)
+            try:
+                await owner.send(
+                    "Your Red instance is out of date! {} is the current "
+                    "version, however you are using {}!".format(
+                        data["info"]["version"], red_version
+                    )
+                )
+            except:
+                pass
         INFO2 = []
 
         sentry = await bot.db.enable_sentry()