add support for Velbus platform (#2830)

* add support for Velbus platform

* Update light.velbus.markdown

* update and extend documentation to be in line with updated pull request for code

* rename fan example to 'Fan 1'

source/_components/binary_sensor.velbus.markdown

@@ -0,0 +1,42 @@
+---
+layout: page
+title: "Velbus sensors"
+description: "Access and control your Velbus sensors."
+date: 2017-06-17 16.58
+sidebar: true
+comments: false
+sharing: true
+footer: true
+logo: velbus.png
+ha_category: Binary Sensor
+ha_iot_class: "Local Push"
+ha_release: 0.49
+---
+
+The `velbus` binary_sensor allows you to control [Velbus](http://www.velbus.eu) connected wall switches.
+
+To use your Velbus wall switches in your installation, add the following to your `configuration.yaml` file:
+
+```yaml
+# Example configuration.yaml entry
+
+binary_sensor:
+  - platform: velbus
+    devices:
+       - name: Wall Switch 1
+         module: 0xda
+         channel: 4
+       - name: Wall Switch 2
+         module: 0xbc
+         channel: 1
+         is_pushbutton: true
+```
+
+Configuration variables:
+- **devices** array (*Required*): The array contains the binary sensors to configure
+  - **name** (*Required*): Name of the binary sensor.
+  - **module** (*Required*): The hexadecimal module address
+  - **channel** (*Required*): The channel number in the module.
+  - **is_pushbutton** (*Optional*): Booelan to indicate if a wall switch is a push button or not (default: false)
+
+For hub configuration, see [the Velbus component](/components/velbus/).