minimal devel documentation in the readme
langid dependency in setup.py
move task routing logic and Elasticsearch stuff to decorator

Also renamed guesslang to langid.
add parameter to routed functions for the body field in ES

I.e., the tasks will now treat doc['_source'][bodyfield] as the body
of a document, where the bodyfield is given in the URL.
fix config task

* in its own module for now
* made debug a main option instead of two (server and worker) options
added /tasklist task for retrieving running and reserved (scheduled) tasks, directly from Celery