Send message to users even if they're not registered to the app

This is because publishing needs to send role requests to users even if
the users have not logged in to publishing.
Store the accounts settings as class attributes in oauth2 client

Instead of storing the settings and passing them in to create the oauth2
client.
Add oauth2 client to request with user's access token set

This creates a new instance of oauth2 client, OpenstaxAccounts, for
every request, and set the access token for the client if it's in the
session.  Previously user's access token was not stored.
Add profile update API to oauth2 client and example app
Merge pull request #10 from Connexions/update-profile-api

Add the update profile API