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.

.coveragerc

@@ -119,6 +119,7 @@ omit =
     homeassistant/components/sensor/arest.py
     homeassistant/components/sensor/bitcoin.py
     homeassistant/components/sensor/cpuspeed.py
+    homeassistant/components/sensor/deutsche_bahn.py
     homeassistant/components/sensor/dht.py
     homeassistant/components/sensor/dweet.py
     homeassistant/components/sensor/efergy.py

homeassistant/components/sensor/deutsche_bahn.py

@@ -0,0 +1,98 @@
+'''
+homeassistant.components.sensor.bahn
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+The deutsche_bahn sensor tells you if your next train is on time, or delayed.
+
+'''
+
+import logging
+from datetime import timedelta, datetime
+from homeassistant.util import Throttle
+from homeassistant.helpers.entity import Entity
+
+_LOGGER = logging.getLogger(__name__)
+REQUIREMENTS = ['schiene==0.14']
+
+ICON = 'mdi:train'
+
+# Return cached results if last scan was less then this time ago
+MIN_TIME_BETWEEN_UPDATES = timedelta(seconds=120)
+
+
+def setup_platform(hass, config, add_devices_callback, discovery_info=None):
+    """ Add the Bahn Sensor. """
+    start = config.get('from')
+    goal = config.get('to')
+
+    if start is None:
+        _LOGGER.error('Missing required variable: "from"')
+        return False
+
+    if goal is None:
+        _LOGGER.error('Missing required variable: "to"')
+        return False
+
+    dev = []
+    dev.append(DeutscheBahnSensor(start, goal))
+    add_devices_callback(dev)
+
+
+# pylint: disable=too-few-public-methods
+class DeutscheBahnSensor(Entity):
+    """Implement a DeutscheBahn  sensor
+    start:     starting station
+    goal:      target station"""
+    def __init__(self, start, goal):
+        self._name = start + ' to ' + goal
+        self.data = SchieneData(start, goal)
+        self.update()
+
+    @property
+    def name(self):
+        """ return the name."""
+        return self._name
+
+    @property
+    def icon(self):
+        """ Icon for the frontend"""
+        return ICON
+
+    @property
+    def state(self):
+        """Return the depature time of the next train"""
+        return self._state
+
+    @property
+    def state_attributes(self):
+        return self.data.connections[0]
+
+    def update(self):
+        """ Gets the latest delay from bahn.de and updates the state"""
+        self.data.update()
+        self._state = self.data.connections[0].get('departure', 'Unknown')
+        delay = self.data.connections[0].get('delay',
+                                             {'delay_departure': 0,
+                                              'delay_arrival': 0})
+        if delay['delay_departure'] != 0:
+            self._state += " + {}".format(delay['delay_departure'])
+
+
+# pylint: disable=too-few-public-methods
+class SchieneData(object):
+    """ Pulls data from the bahn.de web page"""
+    def __init__(self, start, goal):
+        import schiene
+        self.start = start
+        self.goal = goal
+        self.schiene = schiene.Schiene()
+        self.connections = [{}]
+
+    @Throttle(MIN_TIME_BETWEEN_UPDATES)
+    def update(self):
+        """ update connection data"""
+        self.connections = self.schiene.connections(self.start,
+                                                    self.goal,
+                                                    datetime.now())
+        for con in self.connections:
+            if 'details' in con:
+                con.pop('details')  # details info is not usefull

requirements_all.txt

@@ -225,6 +225,9 @@ radiotherm==1.2
 # homeassistant.components.media_player.samsungtv
 samsungctl==0.5.1
 
+# homeassistant.components.sensor.deutsche_bahn
+schiene==0.14
+
 # homeassistant.components.scsgate
 scsgate==0.1.0