Twitter: remove duplicate self.use_oauth checking code
Twitter: remove duplicate self.use_oauth checking code

Just use a new _makeAuthHeader() method for that.

Signed-off-by: Eduardo Habkost <50373d7c08ceadf576dd7dca718012445b677ce6@raisama.net>

praekelt/twitty-twister,dustin/twitty-twister