extended login service to allow users to change their email/login
Broke changeEmail out to its own service and made some general tidy ups as suggested in Katos comments
Tidied up left over code from trying to fix binding issue
reverted test firebase ref to original value INSTANCE
Resolved issue with rebinding user details
Merge pull request #21 from Autodidaktosaur/master

Extended login service to allow users to change their email/login