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/switch.velbus.markdown

@@ -0,0 +1,44 @@
+---
+layout: page
+title: "Velbus Switches"
+description: "Access and control your Velbus Switches."
+date: 2017-06-17 16.58
+sidebar: true
+comments: false
+sharing: true
+footer: true
+logo: velbus.png
+ha_category: Switch
+ha_iot_class: "Local Push"
+ha_release: 0.49
+---
+
+The `velbus` switch allows you to control [Velbus](http://www.velbus.eu) connected switches.
+
+To use your Velbus switches in your installation, add the following to your `configuration.yaml` file:
+
+```yaml
+# Example configuration.yaml entry
+
+light:
+  - platform: velbus
+    devices:
+       - name: Switch 1
+         type: single
+         module: 0xda
+         channel: 4
+       - name: Switch 2
+         type: double
+         module: 0xbc
+         open_channel: 1
+         close_channel: 2
+```
+
+Configuration variables:
+- **devices** array (*Required*): The array contains the switches to configure
+  - **name** (*Required*): Name of the switch.
+  - **module** (*Required*): The hexadecimal module address
+  - **type** (*Required*): Either `single` or `double`. If single, only `channel` attribute is required. If double, both `open_channel` and `close_channel` attributes are required
+  - **channel** (*Required*): The channel number in the module.
+
+For hub configuration, see [the Velbus component](/components/velbus/).