Connect user service with oAuth2

[atompie]

Task

User #244 service instead of current mock-up authorization.

File has a mock-up UserDb object that fetches data from internal dictionary instead of the database.

 def __init__(self):
        self.users_db = UserDb()
        self.token2user = token2user

    def authorize(self, username, password):  # username exists
        if not password:
            raise ValueError("Password empty")

        db_username_record = self.users_db.get_user(username)
        if not db_username_record:
            raise ValueError("Incorrect username or password")

        db_username = db_username_record['username']
        db_password = db_username_record['password']
        db_disabled = db_username_record["disabled"]

        if db_disabled:
            raise ValueError("This account was disabled")

        if db_username != username or db_password != password:
            raise ValueError("Incorrect username or password")

        return db_username_record

Replace this with service form #244