Twitter.__get: rename feed_factory to parser_factory
Twitter.__get: rename feed_factory to parser_factory

The name is clearer about what kind of object it creates.

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

praekelt/twitty-twister,dustin/twitty-twister