Add a rake task to grant permissions to the sync user

Given a user, this task will create authorisations
for all apps with the "update_user_permission"
permission.

This should be run regularly with the API user used
by the app to sync permissions to all the others.
print -> puts
Merge pull request #89 from alphagov/add-signon-permissions-task

Add a rake task to grant permissions to the sync user