Use **type** instead of **account_type** while retrieving an user profile

GhUser is defining **account_type** as attribute, but **account_type** cannot be unserialized directly as the JSON field retrieved from github is **type**.

We could either define a post processor or use back ticks to use type as valid attribute (type is a reserved word). The former has been chosen

Also, a method to retrieve an user profile without access token has been added