Fix Github email stuff

Currently, you are relying on the public email address (if given), which is not validated in any way. Furthermore, you are requesting the API as fallback and use the address, which is marked as `primary`. However, i'm not sure, if `primary` also means `verified`, while there's also a variable, that returns the verification state (according to https://developer.github.com/v3/users/emails/)

The whole block should be rewritten in order to make this work properly.