Added the doc page for GPMDP

source/_components/media_player.gpmdp.markdown

@@ -0,0 +1,37 @@
+---
+layout: page
+title: "Google Play Music Desktop Player (GPMDP)"
+description: "Instructions how to integrate GPMDP into Home Assistant."
+date: 2016-05-09 08:00
+sidebar: true
+comments: false
+sharing: true
+footer: true
+logo: gpmdp.png
+ha_category: Media Player
+ha_iot_class: "Local Polling"
+ha_release: 0.20
+
+---
+
+
+The `GPMDP` platform allows you to control a [GPMDP](http://www.googleplaymusicdesktopplayer.com/) instance running on a computer from Home Assistant.
+
+
+You will have first have to check "Enable playback API" in GPMDP's settings and then add an inbound rule to the firewall to allow access to port 5672 on the computer running GPMDP.
+
+Then just add the following to your `configuration.yaml` file:
+
+```yaml
+# Example configuration.yaml entry
+media_player:
+  platform: gpmdp
+  address: IP_ADDRESS
+  name: NAME
+```
+
+Configuration variables:
+
+- **address** *Required*: IP address of the computer running GPMDP
+- **name** *Optional*: Name of the player
+