Use alertlib (now a submodule) to send to hipchat.

Summary:
With this change, a lot of the files in this repo can go away.
The readme got a lot simpler as well.

Update .gitmodules to get rid of the unneeded python-hipchat submodule.

I though that my 'git rm' would do that, but maybe I was using an old
version of git?

Test Plan:
Ran
   env PYTHONPATH=alertlib:$HOME/khan/webapp python ./notify.py
and saw it send this to both 1s and 0s and 1s/0s: deploys:

Mr Gorilla
10:10 PM
Restarting notify.py!
Mr Gorilla
10:10 PM
App Engine default version just changed: khanacademy.org, appspot dashboard, app versions
• old: None (error logs, instances)
• new: 0722-1740-ed533ed268fd (error logs, instances)

Fingers crossed.

Reviewers: alpert

Reviewed By: alpert

Subscribers: chris

Differential Revision: http://phabricator.khanacademy.org/D11439