Allow oauth signup without email

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Skip require email for devise controllers

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Dont care about emails for oauth

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Add nickname to oauth_spec

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Make oauth works for google oauth too

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Avoid false validation when create user

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Merge branch 'improve-oauth'

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Conflicts:
	CHANGELOG