Document deploying gu:who to a fresh Heroku instance (issue #22)

Requested by Philip Gardner (@NoLogo) :

https://github.com/guardian/gu-who/issues/22

Have run through these steps to confirm they work, the instance is here:

https://gu-who-nologo.herokuapp.com/
Additional explanation around the people repo
Merge pull request #23 from guardian/heroku-deploy

Document deploying gu:who to a fresh Heroku instance (closes issue #22)
Log whether users are in the 'all' team (more debug for issue #21 part II)

Now logging:

* whether users are in the 'all' team
* the permission for the 'all' team, and if it relates to 'people'
* creation of the 'all' team

@timmattison reports that 'gu:who' /only/ successfully creates issues for
Owners of the organisation. This is weird. Maybe the 'all' team does not
have all the access it should.
Merge branch 'master' into wip-tolerate-issue-creation-exception