New deutsche_bahn component

Uses the (schiene)[https://pypi.python.org/pypi/schiene/0.14] API to communicate with the webserver of bahn.de
and pulls iformation about a specific connection from the (bahn.de)[http://www.bahn.de/p/view/index.shtml]
webpage. The departure time of the next train for the given connection is shown.
In case of delay, the delay is also shown. Additional `ATTRIBUTES` are used to
inform about e.g. the type of the train, price and if it is ontime.

Usage:

    sensor:
      platform: deutsche_bahn
        from: name_of_start_station
	  to: name_of_final_station

Problems:
I'm testing it for quite some time, but I have never seen the `ATTRIBUTES` in case
of a delayed train. The `ATTRIBUTES` are directly passed from the `schiene` API. So this
usecase has not been tested yet.

deutsche_bahn ist not supporting the `schiene` api unlike in the swiss_public_transport case.
It's not guaranteed that `schiene` will work forever, infact it can happen that Bahn AG will
intentionally brake the API at some point. In the past Bahn AG has not allways been very supportive
to the opensource community.