Added desc for a permission in GCM Sample Client

Author: Redth

Client.Samples/PushSharp.ClientSample.MonoForAndroid/PushSharp.ClientSample.MonoForAndroid.Gcm/PushService.cs

@@ -13,6 +13,7 @@
 [assembly: UsesPermission(Name = "@[email protected]_MESSAGE")]
 [assembly: UsesPermission(Name = "com.google.android.c2dm.permission.RECEIVE")]
 
+//GET_ACCOUNTS is only needed for android versions 4.0.3 and below
 [assembly: UsesPermission(Name = "android.permission.GET_ACCOUNTS")]
 [assembly: UsesPermission(Name = "android.permission.INTERNET")]
 [assembly: UsesPermission(Name = "android.permission.WAKE_LOCK")]