LabHub: Use activate instead of init

__init__ is executed at load time and
and any issue in the plugin will lead
to it not showing up.
LifeCycle: __init__->configured->enable

Closes #554

plugins/labhub.py

@@ -20,9 +20,7 @@ class LabHub(BotPlugin):
     GH_ORG_NAME = constants.GH_ORG_NAME
     GL_ORG_NAME = constants.GL_ORG_NAME
 
-    def __init__(self, bot, name=None):
-        super().__init__(bot, name)
-
+    def activate(self):
         teams = dict()
         try:
             gh = github3.login(token=os.environ.get('GH_TOKEN'))
@@ -62,6 +60,7 @@ def __init__(self, bot, name=None):
             self.REPOS.update(self.gl_repos)
 
         self.hello_world_users = set()
+        super(LabHub, self).activate()
 
     @property
     def TEAMS(self):