Configuration secrets

As discussed in http://flexget.com/ticket/2523
Plugin mode
manager.py fixed
Remove `Job` class, merge the important bits of it straight to `Task`
Move Tee class to utils
Refactor task queue and execution to be in manager
Strip down scheduler to just queue executions
Fix some references to removed scheduler.execute
Move task execution to own thread to handle signals/ctrl-c gracefully
Move BufferQueue to tools
Actually fix imdb_list with movies with no date.
Fix ipc checking for tasks already in the queue.
Move scheduler starting back to webui code.
Fix for unlikely authentication error.